Speaker
Description
Quantum thermodynamics has recently emerged as a rich field of both fundamental interest and practical utility [1]. Exactly how classical thermodynamics and irreversibility emerge at large scales from unitary quantum mechanics is the subject of current research. At the microscopic level, coherent interactions can be harnessed to build devices such as quantum heat engines or refrigerators that outperform their classical counterparts.
Trapped ion systems are an excellent platform for quantum thermodynamics; they enjoy long coherence times and demonstrate state preparation, measurement, single- and two-qubit gates at high fidelity [2]. Laser pulses can implement Hamiltonian quenches that manipulate the ions' energy landscape, thereby performing microscopic work instantaneously relative to the thermalization time [3]. Furthermore, ground state laser cooling enables coherent control of the ions' harmonic vibrational modes, which provide an additional degree of freedom and all-to-all connectivity between ions in a chain [1].
We present an individually-addressed chain of $^{137}$Ba$^+$ ions as an especially effective system for thermodynamic tasks. Its hyperfine structure ($I=\frac{3}{2}$) and long-lived metastable $D_{5/2}$ manifold permit numerous encoding options for clock qubits across 32 ground and metastable levels. This readily enables mid-circuit measurement, which is crucial for re-thermalizing specific parts of the system and implementing two-point measurement protocols [3]. In addition, we have demonstrated coherent manipulation of higher-dimensional qudit encodings within a single ion [4]. As a result, this platform can realize multi-level thermal machines and measure work and heat statistics in regimes inaccessible to classical systems.
[1] S.Campbell et al., Quantum Science and Technology 11 012501 (2026).
[2] M.Foss-Feig et al., Annual Review Condensed Matter Physics 16:145-72 (2025).
[3] O.Onishchenko et al., Nature Communications 15 6794 (2024).
[4] A. Vazquez-Brennan, PhD thesis. Manuscript in preparation (2026).
| Academic level | PhD student |
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