Artificial quantum thermal bath: Engineering temperature for a many-body quantum system

Abstract

Temperature determines the relative probability of observing a physical system in an energy state when that system is energetically in equilibrium with its environment. In this paper, we present a theory for engineering the temperature of a quantum system different from its ambient temperature. We define criteria for an engineered quantum bath that, when coupled to a quantum system with Hamiltonian H, drives the system to the equilibrium state e −H/T Tr(e −H/T ) with a tunable parameter T . This is basically an analog counterpart of the digital quantum metropolis algorithm. For a system of superconducting qubits, we propose a circuit-QED approximate realization of such an engineered thermal bath consisting of driven lossy resonators. Our proposal opens the path to simulate thermodynamical properties of many-body quantum systems of size not accessible to classical simulations. Also we discuss how an artificial thermal bath can serve as a temperature knob for a hybrid quantum-thermal annealer.

Temperature Control in Dissipative Cavities by Entangled Dimers

“…The above findings identify entangled dimers as an advantageous quantum fuel that may endow photonic heat engines or refrigerators with very high efficiency. Its other possible applications may include quantum simulators for light harvesting complexes [17][18][19][20][21], or thermal quantum annealers [22][23][24]. We conclude and discuss our results, together with suggestions of potential applications, in Sec.…”

“…More specifically, it is proposed in Ref. [24] to use superconducting resonators as thermal baths for finite-temperature quantum annealers. It is, however, also pointed out that resetting the resonator via incoherent thermalization takes too long and hence is the bottleneck against high-speed thermal quantum annealing.…”

Stability Estimates of Markov Semigroups on Abstract States Spaces

“…These kinds of investigations lead to perturbation theory for quantum dynamical systems defined on some operator algebras. Markov chain perturbation bounds, including computational statistics and climate science, see [5,7,23,38,40,41]. We point out that the main results of the present paper also could be applied to the mentioned Markov chains by choosing an appropriate state space.…”

Generating steady quantum coherence and magic through an autonomous thermodynamic machine by utilizing a spin bath

“…Proving the above results from the full steady state solution, which is algebraically messy, is quite challenging. Instead, as a way of simplification, we will follow a perturbative approach, inspired by the fact that the quantum master equation (6) holds true if the interaction strength g is weak. From the general expression for the Bloch vectors of the qubit attached to the heat bath of temperature T 1 , we may write down the leading order terms for the perturbation expansion for small g as -…”

“…Since completely sealing off quantum systems from the environment is very difficult, we may alternately ask -can we somehow use the environment as an ally instead of an impediment [3,4] ? This broad area of research has received renewed attention in recent years with the advent of bath-engineering techniques as well as works on non-Markovian environments [5][6][7][8][9][10][11]. One particular realization in the recent past is of the fact that apart from heat baths, baths such as spin baths can be used to overcome the Landauer erasure energy cost [12][13][14], although a corresponding cost has to be paid in terms of angular momentum.…”