RQI Circuit Stockholm

Contribution List

2. RQI Circuit Stockholm — Opening Remarks

Tales Rick Perche (University of Waterloo)

17/11/2023, 13:00

The RQI Circuit Stockholm will start at 2pm CET and will be broadcast in the ISRQI YouTube Channel. The local organizers are Germain Tobar, Evan Gale, and Vasileios Fragkos.

3. Background Independence and Quantum Causal Structure

Fabio Costa (Stockholm University, Nordita)

17/11/2023, 13:05

Session 1

One of the key ways in which quantum mechanics differs from general relativity is that it requires a fixed background reference frame for spacetime. In fact, this appears to be one of the main conceptual obstacles to uniting the two theories. Additionally, a combination of the two theories is expected to yield `indefinite' causal structures. In this paper, we present a background-independent...

4. Relational Quantum Relativity

Jan Głowacki (CFT PAS, ICTQT)

17/11/2023, 13:30

Session 1

Maybe instead of quantizing relativistic field theories, which we argue to be problematic both conceptually and formally, we could try to relativize the quantum mechanical framework itself? I wish to advertise a research program constituting a direction in the general landscape of the so-called Quantum Reference Frames. The broad idea is to treat reference frames as both physical systems and...

5. Non-Perturbative and Numerical Treatment of Detectors and Fields in Relativistic Scenarios

Robert Jonsson (Stockholm University, Nordita)

17/11/2023, 13:55

Session 1

The mathematical treatment of the interaction between matter and light, especially in relativistic scenarios, is challenging. Even fundamental models, such as the Unruh-DeWitt detector model, present significant obstacles when seeking to treat exactly detector responses, communication scenarios, or entanglement extraction processes.

In many cases, perturbation theory allows for analytic...

6. Localisation problem in Unruh-DeWitt detectors with quantised centre of mass

Evan Gale (University of Queensland)

17/11/2023, 14:20

Session 1

The topic of particle localisation, namely how one defines a position operator or centre of mass in relativistic quantum mechanics, has been a longstanding question in the foundations of quantum mechanics since the mid-20th century. However, despite the length and breadth of study, the localisation problem is still not well understood.

I examine the implications of particle localisation in...

7. Hawking radiation for detectors in superposition of locations outside a black hole

Jerzy Paczos (Stockholm University)

17/11/2023, 15:15

Session 2

Hawking radiation is the proposed thermal black-body radiation of quantum nature emitted from a black hole. One common way to give an account of Hawking radiation is to consider a detector that follows a static trajectory in the vicinity of a black hole and interacts with the quantum field of the radiation. In the present work, we study the Hawking radiation perceived by a detector that...

14. A simple model of a black hole and its radiation

Bo Sundborg (Stockholm University)

17/11/2023, 15:40

Session 2

Free quantum field theories on spheres can be used to model important aspects of black holes. I describe examples which were initially inspired by holography in Anti-De Sitter space and discuss some thermodynamics. I also sketch techniques to operationally test their behaviour by scattering, or by monitoring how they radiate.

8. Gravimetry through nonlinear optomechanics

Sofia Qvarfort (Stockholm University)

17/11/2023, 16:05

Session 2

The large mass of optomechanical systems make them ideal for coupling to and detect weak gravitational fields. In addition, the nonlinear dynamics of the systems offer interesting sensing advantages. In my talk, I will outline the research direction of deriving the fundamental sensing limits of these systems and consider some applications, including to searches of modified gravity theories.

11. A quantum optics approach to testing the GR-QM interface

Igor Pikovski (Stockholm University)

17/11/2023, 16:30

Session 2

In this talk I will give an overview of the work in our group, where we focus on the interface between general relativity and quantum theory at low energies. We study how quantum signatures of gravity can show in table-top experiments, novel phenomena that arise from the interplay of quantum theory and gravity, and a quantum optics approach to physics beyond the Standard Model.

10. Composite quantum particles at the interface with relativity and gravity

Magdalena Zych (Stockholm University)

17/11/2023, 17:40

Session 3

A major goal of modern physics is to understand and test the regime where quantum mechanics and general relativity both play a role. I will discuss why looking at composite particles subject to relativistic effects opens new avenues for conceptual insights into the interface between quantum theory and gravity, for new experiments, and will likely be crucial for next-generation high-precision...

9. Statistical arrow of time and clocks in the quantum regime: a quantum measurements' perspective

Sreenath Kizhakkumpurath Manikandan (Stockholm University, Nordita)

17/11/2023, 18:05

Session 3

In this talk, I will briefly introduce methods to characterize the irreversibility of time-continuous and weak quantum measurements from a thermodynamic viewpoint. By defining a statistical arrow of time for individual realizations of the measurement process, I will show that measurements are absolutely irreversible, similar to the free expansion of a single gas particle in a box. I will...

12. Detecting single gravitons with quantum sensing

Germain Tobar (Stockholm University)

17/11/2023, 18:30

Session 3

The quantisation of gravity is widely believed to result in gravitons -- particles of discrete energy that form gravitational waves. But their detection has so far been considered impossible. Here we show that signatures of single gravitons can be observed in laboratory experiments. We show that stimulated and spontaneous single-graviton processes can become relevant for massive quantum...

13. Gravity is a weirdo!

Guilherme Franzmann (Stockholm University, Nordita)

17/11/2023, 18:55

Session 3

After more than a 100 yrs of General Relativity, we still argue how we should quantize gravity across all possible energy scales. In this talk, I will highlight some of the unexpected features of gravitational phenomena that might be responsible for the hardness of such a task. In particular, I will argue that quantum field theory might not be the correct framework to embed a non-perturbative...

15. Career Development Talk

Magdalena Zych (Stockholm University)

17/11/2023, 19:20

In this talk Magdalena Zych will talk about the career opportunities in Stockholm, and will share important information for researchers who intend to apply for positions in NORDITA and at the University of Stockholm.