Ca+ Coulomb crystals, containing up to a few hundred laser-cooled ions, are used as a cold scaffold to undertake reaction studies between sympathetically cooled, rare gas ions (Xe+
, Kr+ and Ar+) and polar molecules (NH3, ND3, H2O and D2O) [1-3]. The Coulomb crystal environment allows for the accurate calculation of reaction rate coefficients under almost perturbation-free conditions, thanks...
The ALPHA (Antihydrogen Laser PHysics Apparatus) Collaboration at CERN is engaged in precise measurements of the antihydrogen spectrum with a view to studying the fundamental symmetries between matter and antimatter. In 2018, ALPHA measured the 1S-2S transition to one part in 1012 [1]. Since then, ALPHA has gone on to measure the
transitions between the 1S ground state and the 2P1/2 and...
The ALPHA (Antihydrogen Laser Physics Apparatus) collaboration has performed several precision tests of fundamental symmetries through laser and microwave spectroscopy of atomic transitions in the antihydrogen atom [1, 2, 3]. Since typically only around only twenty antihydrogen atoms are trapped per experimental cycle, in these experiments antihydrogen atoms are accumulated [4] over time...
I present a novel scheme for producing cold (magnetically trappable) atomic hydrogen, based on threshold photodissociation of the BaH+ molecular ion. BaH+ can be sympathetically cooled using laser cooled Ba+ in an ion trap, before it is photodissociated on the single photon A1Σ+←X1Σ+ transition. The small mass ratio between Ba+ and BaH+ ensures a strong overlap within the ion trap for...
A practical quantum computer, capable of solving disruptive problems, may require thousands to millions of qubits in order to execute the required quantum error correction. Scaling ion trap quantum computers to larger numbers of qubits has become a prominent area of research [1,2]. However, the number of ions that can be hosted on a single quantum computing module is limited by the size of the...
Trapped Rydberg ions [1] are a novel approach for quantum information processing. By combining the high degree of control of trapped ions with the strong dipolar interaction of Rydberg atoms, fast and motion-independent entangling gates may be realized in large ion crystals.
In our experiment, we excite trapped 88Sr+ ions to Rydberg states. We have observed strong interaction between...
Optical qubit transitions in laser-cooled, trapped ions are used in precision quantum metrology [1] and in quantum information processing [2,3]. In linear ion strings, each qubit and the quantised collective motion are controlled coherently via the ion-laser laser interaction to create scalable entanglement. Such systems could realise a gain in precision and overcome the quantum projection...
A system that can combine the complementary strengths of trapped ions and photons as carriers of quantum information is an appealing prospect. Ions provide long coherence times, high levels of quantum control and high-fidelity state readout, while photons are a natural choice for transmitting information over anything but very short distances. To interface these two platforms we use calcium...
Private communication over shared network infrastructure is of fundamental importance to the modern world. In classical cryptography, shared secrets cannot be created with unconditional security; real-world key exchange protocols rely on computational conjectures such as the hardness of prime factorisation to provide security against eavesdropping attacks. Quantum theory, however, promises...
Optical atomic clocks are our most precise tools to measure time and frequency. Their precision enables frequency comparisons between atoms in separate locations to probe the space-time variation of fundamental constants, the properties of dark matter, and for geodesy. Measurements on independent systems are limited by the standard quantum limit (SQL); measurements on entangled systems, in...
