Probing complex quantum systems

Experimental control has now reached such an exquisite level that synthetic quantum matter can be created by tailoring interactions between individual atoms. These new quantum states of matter might have many interesting and useful properties, but how do we measure them? We use the tools of open quantum systems and quantum metrology to address this problem. We propose new measurement protocols using small quantum systems as probes to extract the energy spectrum or to infer the temperature of many-body systems such as ultracold gases, where strong, short-ranged correlations may confound conventional measurement schemes.

Related work

M. T. Mitchison, A. Purkayastha, M. Brenes, A. Silva, and J. Goold, Taking the temperature of a pure quantum state, arXiv:2103.16601

M. T. Mitchison, T. Fogarty, G. Guarnieri, S. Campbell, Th. Busch, and J. Goold, In situ thermometry of a cold Fermi gas by dephasing impurities, Phys. Rev. Lett. 125, 080402 (2020), arXiv:2004.02911

M. T. Mitchison, T. Johnson, and D. Jaksch, Probing the dynamic structure factor of a neutral Fermi superfluid along the BCS-BEC crossover using atomic impurity qubits, Phys. Rev. A 94, 063618 (2016), arXiv:1609.08131