arXiv subjects

J. K. Thompson

Publications and source records attributed to J. K. Thompson.

6 recordsLinked to original sources

arXiv2024

Continuous momentum state lasing and cavity frequency-pinning with laser-cooled strontium atoms

Laser-cooled gases of atoms interacting with the field of an optical cavity are a powerful tool for quantum sensing and the simulation of open and closed quantum systems. They can display spontaneous self-organisation phase transitions, time crystals, new lasing mechanisms, squeezed states for quantum sensing, protection of quantum coherence, and dynamical phase transitions. However, all of these phenomena are explored in a discontinuous manner due to the need to stop and reload a new ensemble of atoms. Here we report the observation of hours-long continuous lasing from laser-cooled $^{88}$Sr atoms continuously loaded into a ring cavity. The required inversion to produce lasing arises from inversion in the atomic momentum degree of freedom, a mechanism related directly to self-organization phase transitions and collective atomic recoil lasing, both of which were previously only observed in a cyclic fashion compared to the truly continuous behavior here. Further, the sensitivity of the lasing frequency to cavity frequency changes is 120 fold suppressed due to an atomic loss mechanism, opening an interesting new path to compensate cavity frequency noise for realizing narrow frequency references. This work opens the way for continuous cavity QED quantum simulation experiments as well as continuous superradiant lasers.

quant-ph↗

arXiv2024

Entanglement generation in weakly-driven arrays of multilevel atoms via dipolar interactions

We investigate the driven-dissipative dynamics of 1D and 2D arrays of multilevel atoms interacting via dipole-dipole interactions and trapped at subwavelength scales. Here we show that in the weakly driven low excitation regime, multilevel atoms, in contrast to two-level atoms, can become strongly entangled. The entanglement manifests as the growth of collective spin-waves in the ground state manifold, and survives even after turning off the drive. We propose to use the $\sim 2.9~\mu$m transition between $\rm ^3{\rm P}_2 \leftrightarrow \, ^3{\rm D}_3$ in $\rm ^{88}Sr$ with $\rm 389~nm$ trapping light as an ideal experimental platform for validating our predictions and as a novel quantum interface for the exploration of complex many-body phenomena emerging from light-matter interactions.

quant-ph↗

arXiv2022

Emergent dark states from superradiant dynamics in multilevel atoms in a cavity

We investigate the collective decay dynamics of atoms with a generic multilevel structure (angular momenta $F\leftrightarrow F'$) coupled to two light modes of different polarization inside a cavity. In contrast to two-level atoms, we find that multilevel atoms can harbour eigenstates that are perfectly dark to cavity decay even within the subspace of permutationally symmetric states (collective Dicke manifold). The dark states arise from destructive interference between different internal transitions and are shown to be entangled. Remarkably, the superradiant decay of multilevel atoms can end up stuck in one of these dark states, where a macroscopic fraction of the atoms remains excited. This opens the door to the preparation of entangled dark states of matter through collective dissipation useful for quantum sensing and quantum simulation. Our predictions should be readily observable in current optical cavity experiments with alkaline-earth atoms or Raman-dressed transitions.

quant-ph↗

arXiv2019

Single-Particle Decoherence Can Improve Spin-Squeezing Generated In Collective Dynamics

We study the generation of spin-squeezing in arrays of long-lived dipoles subject to collective emission, coherent drive, elastic interactions, and spontaneous emission. Counter-intuitively, it is found that the introduction of spontaneous emission leads to an enhancement of the achievable spin-squeezing, relative to that which emerges in the steady-state of the purely collective dynamics for the same model parameters. This behavior is connected to the dynamical self-tuning of the system through a dissipative phase transition that is present in the collective system alone. Our findings will be applicable to next-generation quantum sensors harnessing correlated quantum matter, including cavity-QED and trapped ion systems.

quant-ph↗

arXiv2018

Robust spin squeezing via photon-mediated interactions on an optical clock transition

Cavity-QED is a promising avenue for the deterministic generation of entangled and spin-squeezed states for quantum metrology. One archetypal scheme generates squeezing via collective one-axis twisting interactions. However, we show that in implementations using optical transitions in long-lived atoms the achievable squeezing is fundamentally limited by collectively enhanced emission into the cavity mode which is generated in parallel with the cavity-mediated spin-spin interactions. We propose an alternative scheme which generates a squeezed state that is protected from collective emission, and investigate its sensitivity to realistic sources of experimental noise and imperfections.

quant-ph↗

arXiv2007

Interfacing Collective Atomic Excitations and Single Photons

We study the performance and limitations of a coherent interface between collective atomic states and single photons. A quantized spin-wave excitation of an atomic sample inside an optical resonator is prepared probabilistically, stored, and adiabatically converted on demand into a sub-Poissonian photonic excitation of the resonator mode. The measured peak single-quantum conversion efficiency of 0.84(11) and its dependence on various parameters are well described by a simple model of the mode geometry and multilevel atomic structure, pointing the way towards implementing high-performance stationary single-photon sources.

physics.atom-ph↗