New physics with superconductor-semiconductor hybrids

• Charles Marcus (Niels Bohr Institute, University of Copenhagen)

Room: Fåhraeus salen In these lectures, I will discuss the consequences of a recent breakthrough in material science, the growth of heterostructures containing superconductors and semiconductors. This includes studies of basic condensed matter physics, such as the superconductor-insulator transition and the so-called anomalous metal phase, to Majorana zero modes and gatemon qubits. In keeping with the theme of the workshop, I will emphasize resent results and opportunities in creating “designer networks” of Josephson junctions.

New physics with superconductor-semiconductor hybrids

• Charles Marcus (Niels Bohr Institute, University of Copenhagen)

Room: Fåhraeus salen In these lectures, I will discuss the consequences of a recent breakthrough in material science, the growth of heterostructures containing superconductors and semiconductors. This includes studies of basic condensed matter physics, such as the superconductor-insulator transition and the so-called anomalous metal phase, to Majorana zero modes and gatemon qubits. In keeping with the theme of the workshop, I will emphasize resent results and opportunities in creating “designer networks” of Josephson junctions.

Superconducting Qubits

• Martinis John (University of California, Santa Barbara)

Room: Fåhraeus salen I will describe the basic physics of superconducting qubits, from a practical and intuitive point of view describing them as non-linear oscillators. I will also review the theory of the surface code, which is a good way to understand how fault-tolerant error correction works. All of this is put together in a review of the quantum supremacy experiment, where high-fidelity qubit operations are possible in a scalable system.

Superconducting Qubits

• John Martinis (University of California, Santa Barbara)

Room: Fåhraeus salen I will describe the basic physics of superconducting qubits, from a practical and intuitive point of view describing them as non-linear oscillators. I will also review the theory of the surface code, which is a good way to understand how fault-tolerant error correction works. All of this is put together in a review of the quantum supremacy experiment, where high-fidelity qubit operations are possible in a scalable system.

BEC-BCS Crossover and the Unitary Fermi Gas

• Zwierlein Martin (Massachusetts Institute of Technology)

Room: Fåhraeus salen ?

Realization of the Fermi-Hubbard Model with Quantum Gases

• Zwierlein Martin (Massachusetts Institute of Technology)

Room: Fåhraeus salen ?

New physics with superconductor-semiconductor hybrids

• Charles Marcus (University of Copenhagen)

Room: Fåhraeus salen In these lectures, I will discuss the consequences of a recent breakthrough in material science, the growth of heterostructures containing superconductors and semiconductors. This includes studies of basic condensed matter physics, such as the superconductor-insulator transition and the so-called anomalous metal phase, to Majorana zero modes and gatemon qubits. In keeping with the theme of the workshop, I will emphasize resent results and opportunities in creating “designer networks” of Josephson junctions.

New physics with superconductor-semiconductor hybrids

• Charles Marcus (University of Copenhagen)

Room: Fåhraeus salen In these lectures, I will discuss the consequences of a recent breakthrough in material science, the growth of heterostructures containing superconductors and semiconductors. This includes studies of basic condensed matter physics, such as the superconductor-insulator transition and the so-called anomalous metal phase, to Majorana zero modes and gatemon qubits. In keeping with the theme of the workshop, I will emphasize resent results and opportunities in creating “designer networks” of Josephson junctions.

Superconducting Qubits

• John Martinis (University of California, Santa Barbara)

Room: Fåhraeus salen I will describe the basic physics of superconducting qubits, from a practical and intuitive point of view describing them as non-linear oscillators. I will also review the theory of the surface code, which is a good way to understand how fault-tolerant error correction works. All of this is put together in a review of the quantum supremacy experiment, where high-fidelity qubit operations are possible in a scalable system.

Superconducting Qubits

• John Martinis (University of California, Santa Barbara)

Room: Fåhraeus salen I will describe the basic physics of superconducting qubits, from a practical and intuitive point of view describing them as non-linear oscillators. I will also review the theory of the surface code, which is a good way to understand how fault-tolerant error correction works. All of this is put together in a review of the quantum supremacy experiment, where high-fidelity qubit operations are possible in a scalable system.

Fractionalization of charge and statistics in two dimensions

• Michael Manfra (Purdue University)

Room: Fåhraeus salen A basic tenet of quantum mechanics is that all elementary particles are either bosons or fermions. Ensembles of bosons and fermions may act differently due to differences in their underlying statistical properties. For example, much of the electronic structure of ordinary solids may be explained by symmetry and noting electrons are fermions and obey the Pauli exclusion principle – fermions cannot exist in the same quantum state simultaneously. On the other hand, integral spin atoms and photons are bosons and are not constrained by the Pauli principle. Bose-Einstein condensation and superfluidity are some of the most spectacular properties of bosons. Starting in the early 1980’s it was theoretically conjectured that excitations that are neither bosons nor fermions may exist under special conditions in two dimensional systems. These unusual excitations were dubbed “anyons” by Frank Wilczek. Anyons may have fractional charge and fractional statistics, however directly probing these properties presents experimental challenges. My lectures will focus on experiments that demonstrate fractional statistics have observable consequences for the two-dimensional electron gas in the fractional quantum Hall regime. While theory indicated the necessity of anyons from the earliest days of the fractional quantum Hall effect, experimental verification has required many advances in materials, experimental probes, and understanding of the operation of electronic Fabry-Perot interferometers in the quantum Hall regime in real devices. I hope to describe how these challenges were met through the work of many groups over the last few decades and outline the physics that remains to be explored in future generations of experiments.

Fractionalization of charge and statistics in two dimensions

• Michael Manfra (Purdue University)

Room: Fåhraeus salen A basic tenet of quantum mechanics is that all elementary particles are either bosons or fermions. Ensembles of bosons and fermions may act differently due to differences in their underlying statistical properties. For example, much of the electronic structure of ordinary solids may be explained by symmetry and noting electrons are fermions and obey the Pauli exclusion principle – fermions cannot exist in the same quantum state simultaneously. On the other hand, integral spin atoms and photons are bosons and are not constrained by the Pauli principle. Bose-Einstein condensation and superfluidity are some of the most spectacular properties of bosons. Starting in the early 1980’s it was theoretically conjectured that excitations that are neither bosons nor fermions may exist under special conditions in two dimensional systems. These unusual excitations were dubbed “anyons” by Frank Wilczek. Anyons may have fractional charge and fractional statistics, however directly probing these properties presents experimental challenges. My lectures will focus on experiments that demonstrate fractional statistics have observable consequences for the two-dimensional electron gas in the fractional quantum Hall regime. While theory indicated the necessity of anyons from the earliest days of the fractional quantum Hall effect, experimental verification has required many advances in materials, experimental probes, and understanding of the operation of electronic Fabry-Perot interferometers in the quantum Hall regime in real devices. I hope to describe how these challenges were met through the work of many groups over the last few decades and outline the physics that remains to be explored in future generations of experiments.

Exploring the gravity-quantum interface at low energies

• Igor Pikovski (Stockholm University)

Room: Fåhraeus salen The search for a quantum theory of gravity is one of the main challenges of modern physics. One major challenge is the lack of observable signatures that can guide theoretical developments. But in recent years, the interplay between quantum physics and general relativity at low energies has emerged as a promising new cross-disciplinary research field. The rapid progress in experimental control of quantum systems at novel scales, and a fresh quantum information perspective, have opened new opportunities for table-top tests to shine some light on this mostly unexplored regime of physics. In this lecture series, I will discuss some examples of this new field, from tests of Post-Newtonian quantum dynamics to quantum gravity phenomenology.

Exploring the gravity-quantum interface at low energies

• Igor Pikovski (Stockholm University)

Room: Fåhraeus salen The search for a quantum theory of gravity is one of the main challenges of modern physics. One major challenge is the lack of observable signatures that can guide theoretical developments. But in recent years, the interplay between quantum physics and general relativity at low energies has emerged as a promising new cross-disciplinary research field. The rapid progress in experimental control of quantum systems at novel scales, and a fresh quantum information perspective, have opened new opportunities for table-top tests to shine some light on this mostly unexplored regime of physics. In this lecture series, I will discuss some examples of this new field, from tests of Post-Newtonian quantum dynamics to quantum gravity phenomenology.

Fractional statistics

• Martin Greiter (Julius-Maximilians-Universität)

Room: Fåhraeus salen In two and one spatial dimensions, we have the possibility of anyon statistics, that is, quantum statistics of identical particles which interpolates between the canonical choices of fermions and bosons. The mathematical reason is that in a path integral formulation, the group describing interchanges is not the permutation, but the braid group, which, in two dimensions, has a continuum of one-dimensional representation labeled by a U(1) phase parameter θ. Physically, this statistical parameter describes the phase acquired by the wave function as we interchange two anyons by winding them counterclockwise around each other. This phase leads to a fractional shift in the allowed values for the relative angular momenta. Anyons can be realized by composites consisting of electric charge and infinitesimally thin magnetic flux tubes. Restrictions for fractional statistics on closed surfaces can be traced back to Dirac’s monopole condition. In field theory, statistical transmutations, and in particular anyon statistics, can be implemented very naturally by a Chern-Simons term in a fictitious gauge field, which attaches both charge and flux tubes to the particles. The quasi particle excitations of fractionally quantized Hall states obey anyon statistics. In one dimension, the crossings of anyons on a ring are always uni-directional, such that a fractional phase θ acquired upon interchange gives rise to fractional shifts in the relative momenta between the anyons. In non-Abelian generalizations, anyons span an internal space of (degenerate) states and transform under higher dimensional representations of the braid group as we wind them around each other. Since the internal state vector is insensitive to local perturbations, non-Abelian anyons may prove instrumental in the construction of fault-tolerant quantum computers.

Fractional statistics

• Martin Greiter (Julius-Maximilians-Universität)

Room: Fåhraeus salen In two and one spatial dimensions, we have the possibility of anyon statistics, that is, quantum statistics of identical particles which interpolates between the canonical choices of fermions and bosons. The mathematical reason is that in a path integral formulation, the group describing interchanges is not the permutation, but the braid group, which, in two dimensions, has a continuum of one-dimensional representation labeled by a U(1) phase parameter θ. Physically, this statistical parameter describes the phase acquired by the wave function as we interchange two anyons by winding them counterclockwise around each other. This phase leads to a fractional shift in the allowed values for the relative angular momenta. Anyons can be realized by composites consisting of electric charge and infinitesimally thin magnetic flux tubes. Restrictions for fractional statistics on closed surfaces can be traced back to Dirac’s monopole condition. In field theory, statistical transmutations, and in particular anyon statistics, can be implemented very naturally by a Chern-Simons term in a fictitious gauge field, which attaches both charge and flux tubes to the particles. The quasi particle excitations of fractionally quantized Hall states obey anyon statistics. In one dimension, the crossings of anyons on a ring are always uni-directional, such that a fractional phase θ acquired upon interchange gives rise to fractional shifts in the relative momenta between the anyons. In non-Abelian generalizations, anyons span an internal space of (degenerate) states and transform under higher dimensional representations of the braid group as we wind them around each other. Since the internal state vector is insensitive to local perturbations, non-Abelian anyons may prove instrumental in the construction of fault-tolerant quantum computers.

Quantum thermodynamics

• Nicole Yunger Halpern (University of Maryland - College Park)

Room: Fåhraeus salen Thermodynamics has shed light on engines, efficiency, and time’s arrow since the Industrial Revolution. But the steam engines that powered the Industrial Revolution were large and classical. Much of today’s technology and experiments are small-scale, quantum, far from equilibrium, and processing information. Nineteenth-century thermodynamics needs re-envisioning for the 21st century. Guidance has come from the mathematical toolkit of quantum information theory. Applying quantum information theory to thermodynamics sheds light on fundamental questions (e.g., how does entanglement spread during quantum thermalization? How can we distinguish quantum heat from quantum work?) and practicalities (e.g., quantum engines and the thermodynamic value of coherences). I will overview how quantum information theory is being used to revolutionize thermodynamics. Recommended reading: Yunger Halpern, Quantum Steampunk: The Physics of Yesterday’s Tomorrow, Johns Hopkins U. Press (2022).

Quantum thermodynamics

• Nicole Yunger Halpern (University of Maryland - College Park)

Room: Fåhraeus salen Thermodynamics has shed light on engines, efficiency, and time’s arrow since the Industrial Revolution. But the steam engines that powered the Industrial Revolution were large and classical. Much of today’s technology and experiments are small-scale, quantum, far from equilibrium, and processing information. Nineteenth-century thermodynamics needs re-envisioning for the 21st century. Guidance has come from the mathematical toolkit of quantum information theory. Applying quantum information theory to thermodynamics sheds light on fundamental questions (e.g., how does entanglement spread during quantum thermalization? How can we distinguish quantum heat from quantum work?) and practicalities (e.g., quantum engines and the thermodynamic value of coherences). I will overview how quantum information theory is being used to revolutionize thermodynamics. Recommended reading: Yunger Halpern, Quantum Steampunk: The Physics of Yesterday’s Tomorrow, Johns Hopkins U. Press (2022).

Quantum-optical topological states in arrays of qubits

• Maxim Gorlach

Room: Fåhraeus salen

Quantum Simulations and Quantum Error Correction with Bosonic Modes

• Steve Girvin (Yale University)

Room: Fåhraeus salen It is well-known that fermions are difficult to simulate with qubits because of their odd symmetry under exchange. It is less widely appreciated that bosons, despite their even symmetry under exchange, are also difficult to simulate with qubits. I will discuss how quantum hardware containing bosonic modes (microwave resonators) offers great hardware efficiency for simulation of many-body and lattice gauge models containing bosons. Time permitting, I will also discuss recent experimental success in quantum error correction beyond the break-even point using the GKP bosonic code.

Quantum Simulations and Quantum Error Correction with Bosonic Modes

• Steve Girvin (Yale University)

Room: Fåhraeus salen It is well-known that fermions are difficult to simulate with qubits because of their odd symmetry under exchange. It is less widely appreciated that bosons, despite their even symmetry under exchange, are also difficult to simulate with qubits. I will discuss how quantum hardware containing bosonic modes (microwave resonators) offers great hardware efficiency for simulation of many-body and lattice gauge models containing bosons. Time permitting, I will also discuss recent experimental success in quantum error correction beyond the break-even point using the GKP bosonic code.

Fractionalization of charge and statistics in two dimensions

• Michael Manfra (Purdue University)

Room: Fåhraeus salen A basic tenet of quantum mechanics is that all elementary particles are either bosons or fermions. Ensembles of bosons and fermions may act differently due to differences in their underlying statistical properties. For example, much of the electronic structure of ordinary solids may be explained by symmetry and noting electrons are fermions and obey the Pauli exclusion principle – fermions cannot exist in the same quantum state simultaneously. On the other hand, integral spin atoms and photons are bosons and are not constrained by the Pauli principle. Bose-Einstein condensation and superfluidity are some of the most spectacular properties of bosons. Starting in the early 1980’s it was theoretically conjectured that excitations that are neither bosons nor fermions may exist under special conditions in two dimensional systems. These unusual excitations were dubbed “anyons” by Frank Wilczek. Anyons may have fractional charge and fractional statistics, however directly probing these properties presents experimental challenges. My lectures will focus on experiments that demonstrate fractional statistics have observable consequences for the two-dimensional electron gas in the fractional quantum Hall regime. While theory indicated the necessity of anyons from the earliest days of the fractional quantum Hall effect, experimental verification has required many advances in materials, experimental probes, and understanding of the operation of electronic Fabry-Perot interferometers in the quantum Hall regime in real devices. I hope to describe how these challenges were met through the work of many groups over the last few decades and outline the physics that remains to be explored in future generations of experiments.

Fractionalization of charge and statistics in two dimensions

• Michael Manfra (Purdue University)

Room: Fåhraeus salen A basic tenet of quantum mechanics is that all elementary particles are either bosons or fermions. Ensembles of bosons and fermions may act differently due to differences in their underlying statistical properties. For example, much of the electronic structure of ordinary solids may be explained by symmetry and noting electrons are fermions and obey the Pauli exclusion principle – fermions cannot exist in the same quantum state simultaneously. On the other hand, integral spin atoms and photons are bosons and are not constrained by the Pauli principle. Bose-Einstein condensation and superfluidity are some of the most spectacular properties of bosons. Starting in the early 1980’s it was theoretically conjectured that excitations that are neither bosons nor fermions may exist under special conditions in two dimensional systems. These unusual excitations were dubbed “anyons” by Frank Wilczek. Anyons may have fractional charge and fractional statistics, however directly probing these properties presents experimental challenges. My lectures will focus on experiments that demonstrate fractional statistics have observable consequences for the two-dimensional electron gas in the fractional quantum Hall regime. While theory indicated the necessity of anyons from the earliest days of the fractional quantum Hall effect, experimental verification has required many advances in materials, experimental probes, and understanding of the operation of electronic Fabry-Perot interferometers in the quantum Hall regime in real devices. I hope to describe how these challenges were met through the work of many groups over the last few decades and outline the physics that remains to be explored in future generations of experiments.

Topological superconductivity

• Annica Black-Schaffer (Uppsala University)

Room: Fåhraeus salen Topological states of matter have emerged in the last decade as one of the absolute most vibrant areas of condensed matter physics. These range from topological insulators and Weyl semimetals but also an abundance of different topological states in superconductors. The defining property for all these phases of matter is a global non-trivial topology of their electronic structure. This is fundamentally different from the traditional Landau paradigm traditionally used to classify matter, where local order parameters appearing due to spontaneous symmetry breaking play the key role. Topological superconductors are particularly interesting as they automatically join these two fundamentally different views of matter having both a global topological order and a local superconducting order parameter. Combining this with the distinctive particle-hole mixing in superconductors gives rise to emergent Majorana fermion states, that can be viewed as half electron quasiparticles offering unique possibilities to realize robust quantum computation. In these lectures I will cover the basic theory of topological superconductivity. Starting from an elementary understanding of conventional BCS superconductivity and topological insulators, I will discuss several different topological superconducting states, as well as focusing on how and why Majorana fermions appear as topological protected edge states.

Topological superconductivity

• Annica Black-Schaffer (Uppsala University)

Room: Fåhraeus salen Topological states of matter have emerged in the last decade as one of the absolute most vibrant areas of condensed matter physics. These range from topological insulators and Weyl semimetals but also an abundance of different topological states in superconductors. The defining property for all these phases of matter is a global non-trivial topology of their electronic structure. This is fundamentally different from the traditional Landau paradigm traditionally used to classify matter, where local order parameters appearing due to spontaneous symmetry breaking play the key role. Topological superconductors are particularly interesting as they automatically join these two fundamentally different views of matter having both a global topological order and a local superconducting order parameter. Combining this with the distinctive particle-hole mixing in superconductors gives rise to emergent Majorana fermion states, that can be viewed as half electron quasiparticles offering unique possibilities to realize robust quantum computation. In these lectures I will cover the basic theory of topological superconductivity. Starting from an elementary understanding of conventional BCS superconductivity and topological insulators, I will discuss several different topological superconducting states, as well as focusing on how and why Majorana fermions appear as topological protected edge states.

Topological superconductors and Majorana fermions Or Odd-frequency superconductivity

• Annica Black-Schaffer (Uppsala University)

Room: Fåhraeus salen

Topological superconductors and Majorana fermions Or Odd-frequency superconductivity

• Annica Black-Schaffer (Uppsala University)

Room: Fåhraeus salen

Quantum Simulations and Quantum Error Correction with Bosonic Modes

• Steve Girvin (Yale University)

Room: Fåhraeus salen It is well-known that fermions are difficult to simulate with qubits because of their odd symmetry under exchange. It is less widely appreciated that bosons, despite their even symmetry under exchange, are also difficult to simulate with qubits. I will discuss how quantum hardware containing bosonic modes (microwave resonators) offers great hardware efficiency for simulation of many-body and lattice gauge models containing bosons. Time permitting, I will also discuss recent experimental success in quantum error correction beyond the break-even point using the GKP bosonic code.

Quantum Simulations and Quantum Error Correction with Bosonic Modes

• Steve Girvin (Yale University)

Room: Fåhraeus salen It is well-known that fermions are difficult to simulate with qubits because of their odd symmetry under exchange. It is less widely appreciated that bosons, despite their even symmetry under exchange, are also difficult to simulate with qubits. I will discuss how quantum hardware containing bosonic modes (microwave resonators) offers great hardware efficiency for simulation of many-body and lattice gauge models containing bosons. Time permitting, I will also discuss recent experimental success in quantum error correction beyond the break-even point using the GKP bosonic code.

Exceptional Topology of Non-Hermitian Systems

• Emil Bergholtz (Stockholm University)

Room: Fåhraeus salen Non-Hermitian “Hamiltonians” occur in the effective description of various physical settings ranging from classical photonics to quantum materials. Using simple examples, I will discuss topological aspects of such systems related to the non-Hermitian concept of exceptional degeneracies at which both eigenvalues and eigenvectors coalesce. I will also discuss how the bulk-boundary correspondence is modified in non-Hermitian systems and how this might be harnessed in novel sensor devices.

Exceptional Topology of Non-Hermitian Systems

• Emil Bergholtz (Stockholm University)

Room: Fåhraeus salen Non-Hermitian “Hamiltonians” occur in the effective description of various physical settings ranging from classical photonics to quantum materials. Using simple examples, I will discuss topological aspects of such systems related to the non-Hermitian concept of exceptional degeneracies at which both eigenvalues and eigenvectors coalesce. I will also discuss how the bulk-boundary correspondence is modified in non-Hermitian systems and how this might be harnessed in novel sensor devices.

In two and one spatial dimensions...

• Martin Greiter (Julius-Maximilians-Universität)

Room: Fåhraeus salen In two and one spatial dimensions, we have the possibility of anyon statistics, that is, quantum statistics of identical particles which interpolates between the canonical choices of fermions and bosons. The mathematical reason is that in a path integral formulation, the group describing interchanges is not the permutation, but the braid group, which, in two dimensions, has a continuum of one-dimensional representation labeled by a U(1) phase parameter θ. Physically, this statistical parameter describes the phase acquired by the wave function as we interchange two anyons by winding them counterclockwise around each other. This phase leads to a fractional shift in the allowed values for the relative angular momenta. Anyons can be realized by composites consisting of electric charge and infinitesimally thin magnetic flux tubes. Restrictions for fractional statistics on closed surfaces can be traced back to Dirac’s monopole condition. In field theory, statistical transmutations, and in particular anyon statistics, can be implemented very naturally by a Chern-Simons term in a fictitious gauge field, which attaches both charge and flux tubes to the particles. The quasi particle excitations of fractionally quantized Hall states obey anyon statistics. In one dimension, the crossings of anyons on a ring are always uni-directional, such that a fractional phase θ acquired upon interchange gives rise to fractional shifts in the relative momenta between the anyons. In non-Abelian generalizations, anyons span an internal space of (degenerate) states and transform under higher dimensional representations of the braid group as we wind them around each other. Since the internal state vector is insensitive to local perturbations, non-Abelian anyons may prove instrumental in the construction of fault-tolerant quantum computers.

In two and one spatial dimensions...

• Martin Greiter (Julius-Maximilians-Universität)

Room: Fåhraeus salen In two and one spatial dimensions, we have the possibility of anyon statistics, that is, quantum statistics of identical particles which interpolates between the canonical choices of fermions and bosons. The mathematical reason is that in a path integral formulation, the group describing interchanges is not the permutation, but the braid group, which, in two dimensions, has a continuum of one-dimensional representation labeled by a U(1) phase parameter θ. Physically, this statistical parameter describes the phase acquired by the wave function as we interchange two anyons by winding them counterclockwise around each other. This phase leads to a fractional shift in the allowed values for the relative angular momenta. Anyons can be realized by composites consisting of electric charge and infinitesimally thin magnetic flux tubes. Restrictions for fractional statistics on closed surfaces can be traced back to Dirac’s monopole condition. In field theory, statistical transmutations, and in particular anyon statistics, can be implemented very naturally by a Chern-Simons term in a fictitious gauge field, which attaches both charge and flux tubes to the particles. The quasi particle excitations of fractionally quantized Hall states obey anyon statistics. In one dimension, the crossings of anyons on a ring are always uni-directional, such that a fractional phase θ acquired upon interchange gives rise to fractional shifts in the relative momenta between the anyons. In non-Abelian generalizations, anyons span an internal space of (degenerate) states and transform under higher dimensional representations of the braid group as we wind them around each other. Since the internal state vector is insensitive to local perturbations, non-Abelian anyons may prove instrumental in the construction of fault-tolerant quantum computers.

Time Reversal Symmetry and Its Breaking

• Frank Wilczek (Stockholm University)

Room: Fåhraeus salen I will give two lectures centered on time reversal symmetry T and its breaking. The overwhelming emphasis will be on non-dissipative dynamics. In the first lecture, after briefly reviewing time reversal symmetry in classical physics and elementary quantum mechanics, I will turn to the issue of T in the standard model. I will derive the “main theorem of the standard model”, which puts the interactions allowed by general principles into a simple canonical form. This will pinpoint the origin of observed fundamental T violation and the motivation for Peccei-Quinn symmetry and axion physics. In the second lecture I will discuss, mainly through a couple of case studies, how T symmetry figures into the analysis of matter. Specifically, I will discuss a canonical model of charge fractionalization (inspired by polyacetylene) and the issue of whether biology might have, in addition to its well-known chirality, also “temporal chirality”. The systematic use of effective Lagrangians will be a unifying pedagogical theme.

Time Reversal Symmetry and Its Breaking

• Frank Wilczek (Stockholm University)

Room: Fåhraeus salen I will give two lectures centered on time reversal symmetry T and its breaking. The overwhelming emphasis will be on non-dissipative dynamics. In the first lecture, after briefly reviewing time reversal symmetry in classical physics and elementary quantum mechanics, I will turn to the issue of T in the standard model. I will derive the “main theorem of the standard model”, which puts the interactions allowed by general principles into a simple canonical form. This will pinpoint the origin of observed fundamental T violation and the motivation for Peccei-Quinn symmetry and axion physics. In the second lecture I will discuss, mainly through a couple of case studies, how T symmetry figures into the analysis of matter. Specifically, I will discuss a canonical model of charge fractionalization (inspired by polyacetylene) and the issue of whether biology might have, in addition to its well-known chirality, also “temporal chirality”. The systematic use of effective Lagrangians will be a unifying pedagogical theme.

Superoscillations old and new

• Michael Berry (University of Bristol)

Room: Fåhraeus salen This concerns a substantial and fast-developing area, in which the concept of functions that vary faster than they should connects a number of subjects conventionally regarded as separate: quantum physics, optical singularities, mathematical function theory, superresolution microscopy, radar theory... The connections provide a wonderful illustration of the unity of different areas of mathematics and physics. F.C. Frank: “Physics is not just Concerning the Nature of Things, but Concerning the Interconnectedness of all the Natures of Things”

Superoscillations old and new

• Michael Berry (University of Bristol)

Room: Fåhraeus salen This concerns a substantial and fast-developing area, in which the concept of functions that vary faster than they should connects a number of subjects conventionally regarded as separate: quantum physics, optical singularities, mathematical function theory, superresolution microscopy, radar theory... The connections provide a wonderful illustration of the unity of different areas of mathematics and physics. F.C. Frank: “Physics is not just Concerning the Nature of Things, but Concerning the Interconnectedness of all the Natures of Things”

A beginners guide to wavelike dark matter experiments

• Alexander Millar (Stockholm University)

Room: Fåhraeus salen I will introduce wavelike dark matter, with a particular emphasis on axions, axion-like particles and hidden photons. I will outline the primary search strategies (experimental, astrophysical and cosmological) and explore many of the recent developments in the experimental landscape. Finally, I will go through a pedagogical example of a new kind of experiment, with emphasis on the development process rather than physics.

A beginners guide to wavelike dark matter experiments

• Alexander Millar (Stockholm University)

Room: Fåhraeus salen I will introduce wavelike dark matter, with a particular emphasis on axions, axion-like particles and hidden photons. I will outline the primary search strategies (experimental, astrophysical and cosmological) and explore many of the recent developments in the experimental landscape. Finally, I will go through a pedagogical example of a new kind of experiment, with emphasis on the development process rather than physics.

Metamaterials: from left-handed media to hyperbolic metamaterials

• Pavel Belov (ITMO University)

Room: Fåhraeus salen The metamaterials are artificially created materials with electromagnetic properties not readily available in natural media. The metamaterials allow to control electromagnetic waves in unprecedented ways: one can create flat lenses with subwavelength resolution, dramatically modify spontaneous emission of quantum sources via Purcell effect, negatively refract plane waves and invert phase velocity of light. These effects which seemed impossible for a long time now become common and many new devices start to employ them. The special kind of metamaterials, so-called wire medtamaterials are composed of metallic wires and behave as artificial plasma and feature effects of strong spatial dispersion not observable in any other media. The wire media have found tremendous number of application ranging from magnetic resonance imaging to axion detection. The evolution of metamaterials also led to wide use of their 2d counterparts – metasurfaces. With the help of these planar artificial interfaces one can rotate polarization, filter, refract, focus and localize electromagnetic waves and build many functional devices for variety of diverse applications. Basically, the metamaterials and metasurfaces opened a fundamentally new way to manipulation of electromagnetic waves.

Metamaterials: from left-handed media to hyperbolic metamaterials

• Pavel Belov (ITMO University)

Room: Fåhraeus salen The metamaterials are artificially created materials with electromagnetic properties not readily available in natural media. The metamaterials allow to control electromagnetic waves in unprecedented ways: one can create flat lenses with subwavelength resolution, dramatically modify spontaneous emission of quantum sources via Purcell effect, negatively refract plane waves and invert phase velocity of light. These effects which seemed impossible for a long time now become common and many new devices start to employ them. The special kind of metamaterials, so-called wire medtamaterials are composed of metallic wires and behave as artificial plasma and feature effects of strong spatial dispersion not observable in any other media. The wire media have found tremendous number of application ranging from magnetic resonance imaging to axion detection. The evolution of metamaterials also led to wide use of their 2d counterparts – metasurfaces. With the help of these planar artificial interfaces one can rotate polarization, filter, refract, focus and localize electromagnetic waves and build many functional devices for variety of diverse applications. Basically, the metamaterials and metasurfaces opened a fundamentally new way to manipulation of electromagnetic waves.

A beginners guide to wavelike dark matter experiments

• Alexander Millar (Stockholm University)

Room: Fåhraeus salen I will introduce wavelike dark matter, with a particular emphasis on axions, axion-like particles and hidden photons. I will outline the primary search strategies (experimental, astrophysical and cosmological) and explore many of the recent developments in the experimental landscape. Finally, I will go through a pedagogical example of a new kind of experiment, with emphasis on the development process rather than physics.

A beginners guide to wavelike dark matter experiments

• Alexander Millar (Stockholm University)

Room: Fåhraeus salen I will introduce wavelike dark matter, with a particular emphasis on axions, axion-like particles and hidden photons. I will outline the primary search strategies (experimental, astrophysical and cosmological) and explore many of the recent developments in the experimental landscape. Finally, I will go through a pedagogical example of a new kind of experiment, with emphasis on the development process rather than physics.

Time Reversal Symmetry and Its Breaking

• Frank Wilczek (Stockholm University)

Room: Fåhraeus salen I will give two lectures centered on time reversal symmetry T and its breaking. The overwhelming emphasis will be on non-dissipative dynamics. In the first lecture, after briefly reviewing time reversal symmetry in classical physics and elementary quantum mechanics, I will turn to the issue of T in the standard model. I will derive the “main theorem of the standard model”, which puts the interactions allowed by general principles into a simple canonical form. This will pinpoint the origin of observed fundamental T violation and the motivation for Peccei-Quinn symmetry and axion physics. In the second lecture I will discuss, mainly through a couple of case studies, how T symmetry figures into the analysis of matter. Specifically, I will discuss a canonical model of charge fractionalization (inspired by polyacetylene) and the issue of whether biology might have, in addition to its well-known chirality, also “temporal chirality”. The systematic use of effective Lagrangians will be a unifying pedagogical theme.

Time Reversal Symmetry and Its Breaking

• Frank Wilczek (Stockholm University)

Room: Fåhraeus salen I will give two lectures centered on time reversal symmetry T and its breaking. The overwhelming emphasis will be on non-dissipative dynamics. In the first lecture, after briefly reviewing time reversal symmetry in classical physics and elementary quantum mechanics, I will turn to the issue of T in the standard model. I will derive the “main theorem of the standard model”, which puts the interactions allowed by general principles into a simple canonical form. This will pinpoint the origin of observed fundamental T violation and the motivation for Peccei-Quinn symmetry and axion physics. In the second lecture I will discuss, mainly through a couple of case studies, how T symmetry figures into the analysis of matter. Specifically, I will discuss a canonical model of charge fractionalization (inspired by polyacetylene) and the issue of whether biology might have, in addition to its well-known chirality, also “temporal chirality”. The systematic use of effective Lagrangians will be a unifying pedagogical theme.

Metamaterials: from left-handed media to hyperbolic metamaterials

• Pavel Belov (ITMO University)

Room: Fåhraeus salen The metamaterials are artificially created materials with electromagnetic properties not readily available in natural media. The metamaterials allow to control electromagnetic waves in unprecedented ways: one can create flat lenses with subwavelength resolution, dramatically modify spontaneous emission of quantum sources via Purcell effect, negatively refract plane waves and invert phase velocity of light. These effects which seemed impossible for a long time now become common and many new devices start to employ them. The special kind of metamaterials, so-called wire medtamaterials are composed of metallic wires and behave as artificial plasma and feature effects of strong spatial dispersion not observable in any other media. The wire media have found tremendous number of application ranging from magnetic resonance imaging to axion detection. The evolution of metamaterials also led to wide use of their 2d counterparts – metasurfaces. With the help of these planar artificial interfaces one can rotate polarization, filter, refract, focus and localize electromagnetic waves and build many functional devices for variety of diverse applications. Basically, the metamaterials and metasurfaces opened a fundamentally new way to manipulation of electromagnetic waves.

Metamaterials: from left-handed media to hyperbolic metamaterials

• Pavel Belov (ITMO University)

Room: Fåhraeus salen The metamaterials are artificially created materials with electromagnetic properties not readily available in natural media. The metamaterials allow to control electromagnetic waves in unprecedented ways: one can create flat lenses with subwavelength resolution, dramatically modify spontaneous emission of quantum sources via Purcell effect, negatively refract plane waves and invert phase velocity of light. These effects which seemed impossible for a long time now become common and many new devices start to employ them. The special kind of metamaterials, so-called wire medtamaterials are composed of metallic wires and behave as artificial plasma and feature effects of strong spatial dispersion not observable in any other media. The wire media have found tremendous number of application ranging from magnetic resonance imaging to axion detection. The evolution of metamaterials also led to wide use of their 2d counterparts – metasurfaces. With the help of these planar artificial interfaces one can rotate polarization, filter, refract, focus and localize electromagnetic waves and build many functional devices for variety of diverse applications. Basically, the metamaterials and metasurfaces opened a fundamentally new way to manipulation of electromagnetic waves.

Quantum Steampunk: The Physics of Yesterday’s Tomorrow

• Nicole Yunger Halpern (University of Maryland - College Park)

Room: Fåhraeus salen Thermodynamics has shed light on engines, efficiency, and time’s arrow since the Industrial Revolution. But the steam engines that powered the Industrial Revolution were large and classical. Much of today’s technology and experiments are small-scale, quantum, far from equilibrium, and processing information. Nineteenth-century thermodynamics needs re-envisioning for the 21st century. Guidance has come from the mathematical toolkit of quantum information theory. Applying quantum information theory to thermodynamics sheds light on fundamental questions (e.g., how does entanglement spread during quantum thermalization? How can we distinguish quantum heat from quantum work?) and practicalities (e.g., quantum engines and the thermodynamic value of coherences). I will overview how quantum information theory is being used to revolutionize Thermodynamics.

Quantum Steampunk: The Physics of Yesterday’s Tomorrow

• Nicole Yunger Halpern (University of Maryland - College Park)

Room: Fåhraeus salen Thermodynamics has shed light on engines, efficiency, and time’s arrow since the Industrial Revolution. But the steam engines that powered the Industrial Revolution were large and classical. Much of today’s technology and experiments are small-scale, quantum, far from equilibrium, and processing information. Nineteenth-century thermodynamics needs re-envisioning for the 21st century. Guidance has come from the mathematical toolkit of quantum information theory. Applying quantum information theory to thermodynamics sheds light on fundamental questions (e.g., how does entanglement spread during quantum thermalization? How can we distinguish quantum heat from quantum work?) and practicalities (e.g., quantum engines and the thermodynamic value of coherences). I will overview how quantum information theory is being used to revolutionize Thermodynamics.

Superoscillations old and new

• Michael Berry (University of Bristol)

Room: Fåhraeus salen This concerns a substantial and fast-developing area, in which the concept of functions that vary faster than they should connects a number of subjects conventionally regarded as separate: quantum physics, optical singularities, mathematical function theory, superresolution microscopy, radar theory... The connections provide a wonderful illustration of the unity of different areas of mathematics and physics. F.C. Frank: “Physics is not just Concerning the Nature of Things, but Concerning the Interconnectedness of all the Natures of Things”

Superoscillations old and new

• Michael Berry (University of Bristol)

Room: Fåhraeus salen This concerns a substantial and fast-developing area, in which the concept of functions that vary faster than they should connects a number of subjects conventionally regarded as separate: quantum physics, optical singularities, mathematical function theory, superresolution microscopy, radar theory... The connections provide a wonderful illustration of the unity of different areas of mathematics and physics. F.C. Frank: “Physics is not just Concerning the Nature of Things, but Concerning the Interconnectedness of all the Natures of Things”

Quantum Sensing and Metrology

• Paola Cappellaro (Massachusetts Institute of Technology)

Room: Fåhraeus salen Quantum sensing" describes the use of a quantum system, quantum properties or quantum phenomena to perform a measurement of a physical quantity. More recently, quantum sensing has become a distinct and rapidly growing branch of research within the area of quantum science and technology, with the most common platforms being spin qubits, trapped ions and flux qubits. Quantum sensors can surpass the sensitivity of classical devices, and their ultimate performance is studied in quantum metrology. In addition, quantum sensors can be used to characterize the noise created by their environment, and thus guide the development of error correction strategies. In these lectures, I will provide an introduction to the basic principles, methods and concepts of quantum sensing and metrology.

Quantum Sensing and Metrology

• Paola Cappellaro (Massachusetts Institute of Technology)

Room: Fåhraeus salen Quantum sensing" describes the use of a quantum system, quantum properties or quantum phenomena to perform a measurement of a physical quantity. More recently, quantum sensing has become a distinct and rapidly growing branch of research within the area of quantum science and technology, with the most common platforms being spin qubits, trapped ions and flux qubits. Quantum sensors can surpass the sensitivity of classical devices, and their ultimate performance is studied in quantum metrology. In addition, quantum sensors can be used to characterize the noise created by their environment, and thus guide the development of error correction strategies. In these lectures, I will provide an introduction to the basic principles, methods and concepts of quantum sensing and metrology.

Quantum advantage and quantum simulation with photons and atoms. (via Zoom)

• Jianwei Pan (University of Science and Technology of China)
• Yuao Chen (University of Science and Technology of China)

Room: Fåhraeus salen Quantum computation harnesses the collective properties of quantum states, such as superposition, interference, and entanglement, to perform calculations, can greatly enhance the computing power. Physically, there are many candidates of quantum systems to implement quantum computation and simulation. In this lecture, I will introduce quantum computation and simulation with photons and cold atoms. By developing high-performance quantum light sources, the multi-photon interference has been scaled up to implement boson sampling with up to 76 photons out of a 100-mode interferometer, which yields a Hilbert state space dimension of 1030 and a rate that is 1014 faster than using the state-of-the-art simulation strategy on supercomputers. Such a demonstration of quantum computational advantage is a much-anticipated milestone for quantum computing. The special-purpose photonic platform will be further used to investigate practical applications linked to the Gaussian boson sampling, such as graph optimization and quantum machine learning. Ultracold atoms constitute a unique physical system for studying strongly correlated quantum many-body physics, and promise a great potential for quantum simulation. A new method of staggered-immersion cooling has been demonstrated in experiment leading to dramatic reduction of defects (from 10% to 0.8%) in a 2D lattice of 10k sites. Based on this, 1250 pairs of entangled atoms are prepared with a fidelity of 99.3%. This well-controlled quantum system consisting 71 lattice sites is used to model the Hamiltonian of a 1D lattice gauge theory with gauge symmetry of U(1), the Schwinger model. Furthermore, the properties of LGTs, such as quantum thermalization, have been studied. It is expected that, quantum simulation tasks outperforming relevant numerical calculations with classical supercomputers are likely to be demonstrated with the state-of-the-art cold-atom quantum simulators.

Quantum advantage and quantum simulation with photons and atoms. (via Zoom)

• Jianwei Pan (University of Science and Technology of China)
• Yuao Chen (University of Science and Technology of China)

Room: Fåhraeus salen Quantum computation harnesses the collective properties of quantum states, such as superposition, interference, and entanglement, to perform calculations, can greatly enhance the computing power. Physically, there are many candidates of quantum systems to implement quantum computation and simulation. In this lecture, I will introduce quantum computation and simulation with photons and cold atoms. By developing high-performance quantum light sources, the multi-photon interference has been scaled up to implement boson sampling with up to 76 photons out of a 100-mode interferometer, which yields a Hilbert state space dimension of 1030 and a rate that is 1014 faster than using the state-of-the-art simulation strategy on supercomputers. Such a demonstration of quantum computational advantage is a much-anticipated milestone for quantum computing. The special-purpose photonic platform will be further used to investigate practical applications linked to the Gaussian boson sampling, such as graph optimization and quantum machine learning. Ultracold atoms constitute a unique physical system for studying strongly correlated quantum many-body physics, and promise a great potential for quantum simulation. A new method of staggered-immersion cooling has been demonstrated in experiment leading to dramatic reduction of defects (from 10% to 0.8%) in a 2D lattice of 10k sites. Based on this, 1250 pairs of entangled atoms are prepared with a fidelity of 99.3%. This well-controlled quantum system consisting 71 lattice sites is used to model the Hamiltonian of a 1D lattice gauge theory with gauge symmetry of U(1), the Schwinger model. Furthermore, the properties of LGTs, such as quantum thermalization, have been studied. It is expected that, quantum simulation tasks outperforming relevant numerical calculations with classical supercomputers are likely to be demonstrated with the state-of-the-art cold-atom quantum simulators.

Dynamics of emergent gauge theories, false vacuums and virtual particles. (via Zoom)

• Sid Morampudi (Massachusetts Institute of Technology)

Room: Fåhraeus salen Emergent gauge theories are ubiquitous in modern condensed matter physics under various forms such as quantum spin liquids. I will provide an introduction to how they arise, and the novel dynamics possible in them due to key differences in energy scales compared to the usual gauge theories of high energy physics. In the second part of the lecture, using a simple Ising model as a prototype, I will discuss some tell-tale signatures of how we can know if we are in a false vacuum universe even if the actual decay to the true vacuum takes an absurdly long time. This will illustrate some observable signatures of the dynamics of virtual particles popping in and out of existence.

Dynamics of emergent gauge theories, false vacuums and virtual particles. (via Zoom)

• Sid Morampudi (Massachusetts Institute of Technology)

Room: Fåhraeus salen Emergent gauge theories are ubiquitous in modern condensed matter physics under various forms such as quantum spin liquids. I will provide an introduction to how they arise, and the novel dynamics possible in them due to key differences in energy scales compared to the usual gauge theories of high energy physics. In the second part of the lecture, using a simple Ising model as a prototype, I will discuss some tell-tale signatures of how we can know if we are in a false vacuum universe even if the actual decay to the true vacuum takes an absurdly long time. This will illustrate some observable signatures of the dynamics of virtual particles popping in and out of existence.

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• Paola Cappellaro (Massachusetts Institute of Technology)

Room: Fåhraeus salen ?

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• Paola Cappellaro (Massachusetts Institute of Technology)

Room: Fåhraeus salen ?

Exceptional Topology of Non-Hermitian Systems

• Emil Bergholtz (Stockholm University)

Room: Fåhraeus salen Non-Hermitian “Hamiltonians” occur in the effective description of various physical settings ranging from classical photonics to quantum materials. Using simple examples, I will discuss topological aspects of such systems related to the non-Hermitian concept of exceptional degeneracies at which both eigenvalues and eigenvectors coalesce. I will also discuss how the bulk-boundary correspondence is modified in non-Hermitian systems and how this might be harnessed in novel sensor devices.

Exceptional Topology of Non-Hermitian Systems

• Emil Bergholtz (Stockholm University)

Room: Fåhraeus salen Non-Hermitian “Hamiltonians” occur in the effective description of various physical settings ranging from classical photonics to quantum materials. Using simple examples, I will discuss topological aspects of such systems related to the non-Hermitian concept of exceptional degeneracies at which both eigenvalues and eigenvectors coalesce. I will also discuss how the bulk-boundary correspondence is modified in non-Hermitian systems and how this might be harnessed in novel sensor devices.

Quantum advantage and quantum simulation with photons and atoms. (via Zoom)

• Yuao Chen (University of Science and Technology of China)
• Jianwei Pan (University of Science and Technology of China)

Room: Fåhraeus salen Quantum computation harnesses the collective properties of quantum states, such as superposition, interference, and entanglement, to perform calculations, can greatly enhance the computing power. Physically, there are many candidates of quantum systems to implement quantum computation and simulation. In this lecture, I will introduce quantum computation and simulation with photons and cold atoms. By developing high-performance quantum light sources, the multi-photon interference has been scaled up to implement boson sampling with up to 76 photons out of a 100-mode interferometer, which yields a Hilbert state space dimension of 1030 and a rate that is 1014 faster than using the state-of-the-art simulation strategy on supercomputers. Such a demonstration of quantum computational advantage is a much-anticipated milestone for quantum computing. The special-purpose photonic platform will be further used to investigate practical applications linked to the Gaussian boson sampling, such as graph optimization and quantum machine learning. Ultracold atoms constitute a unique physical system for studying strongly correlated quantum many-body physics, and promise a great potential for quantum simulation. A new method of staggered-immersion cooling has been demonstrated in experiment leading to dramatic reduction of defects (from 10% to 0.8%) in a 2D lattice of 10k sites. Based on this, 1250 pairs of entangled atoms are prepared with a fidelity of 99.3%. This well-controlled quantum system consisting 71 lattice sites is used to model the Hamiltonian of a 1D lattice gauge theory with gauge symmetry of U(1), the Schwinger model. Furthermore, the properties of LGTs, such as quantum thermalization, have been studied. It is expected that, quantum simulation tasks outperforming relevant numerical calculations with classical supercomputers are likely to be demonstrated with the state-of-the-art cold-atom quantum simulators.

Quantum advantage and quantum simulation with photons and atoms. (via Zoom)

• Jianwei Pan (University of Science and Technology of China)
• Yuao Chen (University of Science and Technology of China)

Room: Fåhraeus salen Quantum computation harnesses the collective properties of quantum states, such as superposition, interference, and entanglement, to perform calculations, can greatly enhance the computing power. Physically, there are many candidates of quantum systems to implement quantum computation and simulation. In this lecture, I will introduce quantum computation and simulation with photons and cold atoms. By developing high-performance quantum light sources, the multi-photon interference has been scaled up to implement boson sampling with up to 76 photons out of a 100-mode interferometer, which yields a Hilbert state space dimension of 1030 and a rate that is 1014 faster than using the state-of-the-art simulation strategy on supercomputers. Such a demonstration of quantum computational advantage is a much-anticipated milestone for quantum computing. The special-purpose photonic platform will be further used to investigate practical applications linked to the Gaussian boson sampling, such as graph optimization and quantum machine learning. Ultracold atoms constitute a unique physical system for studying strongly correlated quantum many-body physics, and promise a great potential for quantum simulation. A new method of staggered-immersion cooling has been demonstrated in experiment leading to dramatic reduction of defects (from 10% to 0.8%) in a 2D lattice of 10k sites. Based on this, 1250 pairs of entangled atoms are prepared with a fidelity of 99.3%. This well-controlled quantum system consisting 71 lattice sites is used to model the Hamiltonian of a 1D lattice gauge theory with gauge symmetry of U(1), the Schwinger model. Furthermore, the properties of LGTs, such as quantum thermalization, have been studied. It is expected that, quantum simulation tasks outperforming relevant numerical calculations with classical supercomputers are likely to be demonstrated with the state-of-the-art cold-atom quantum simulators.