Abstract
We propose the simulation of quantum-optical systems in the ultrastrong-coupling regime using a variational quantum algorithm. More precisely, we introduce a short-depth variational form to prepare the groundstate of the multimode Dicke model on a quantum processor and present proof-of-principle results obtained via cloud access to an IBM device. We moreover provide an algorithm for characterizing the groundstate by Wigner state tomography. Our work is a first step towards digital quantum simulation of quantum-optical systems with potential applications to the spin-boson, Kondo and Jahn-Teller models.
Highlights
Quantum simulation is one promising application of quantum processors which aims to circumvent the limitations of classical computers at simulating matter
Many other realizations of what is known as variational quantum algorithm (VQA) have appeared [2,3,4,5]
[2,3,4,5] and optimization [8], the applicability of VQAs to other domains is a subject of debate and interest [9,10]
Summary
Quantum simulation is one promising application of quantum processors which aims to circumvent the limitations of classical computers at simulating matter. Provided that g is greater than the decoherence rates of the atom and the cavity, this regime is referred to as strong coupling, and it is widely exploited for quantum-information processing purposes [17]. In the large-g limit, the mean cavity-mode photon number and its quantum fluctuations become large enough to make the numerical simulation of many-particle systems difficult or unpractical. This motivates the search for efficient analytical and numerical methods [11,12,13,21,22,23,24] and quantum-simulation algorithms [14,15,19,25,26,27]
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