Quantum Computing by Coherent Cooling

Feng, Jingnan; Wu, Biao; Wilczek, Frank

doi:10.1103/physreva.105.052601

Cited by 8 publications

(3 citation statements)

References 69 publications

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“…where the eigenvalues, λ x , are the numerical measurement result. According to quantum collapse theory 17 , an ensemble of impure states is obtained after performing a large number of measurements. This ensemble stands for the initial states {|x 0 ⟩} and serves as the initial conditions for the operating nonlinear transformations.…”

Section: Application To Quantum Computersmentioning

confidence: 99%

Re-Coherence Generated by Nonlinear Maps

Roth

2023

Preprint

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Section: Application To Quantum Computersmentioning

confidence: 99%

Re-Coherence Generated by Nonlinear Maps

Roth

2023

Preprint

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“…In order to find the ground state of the model described by equation (1), in this paper we use an approach that has been termed computing by cooling in [24]: in practice one employs a non-Markovian quantum bath in the form of a spin system with an easy-to-prepare low-temperature state, see a sketch of our proposal in figure 1. Coupling the system represented by the problem Hamiltonian (1) to such a cold bath, the system of interest is thus cooled down toward its ground state.…”

Section: Introductionmentioning

confidence: 99%

A thermodynamic approach to optimization in complex quantum systems

Imparato,

Chancellor,

De Chiara

2024

Quantum Sci. Technol.

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We consider the problem of finding the energy minimum of a complex quantum Hamiltonian byemploying a non-Markovian bath prepared in a low energy state. The energy minimization problemis thus turned into a thermodynamic cooling protocol in which we repeatedly put the system ofinterest in contact with a colder auxiliary system. By tuning the internal parameters of the bath,we show that the optimal cooling is obtained in a regime where the bath exhibits a quantum phasetransition in the thermodynamic limit. This result highlights the importance of collective effects inthermodynamic devices. We furthermore introduce a two-step protocol that combines the interactionwith the bath with a measure of its energy. While this protocol does not destroy coherence in thesystem of interest, we show that it can further enhance the cooling effect.

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“…Recently, algorithms that mimic cooling by coupling to a simulated low-entropy bath [18][19][20][21][22][23][24] have been proposed as alternative routes that may overcome some of these challenges.…”

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confidence: 99%

Programmable adiabatic demagnetization for systems with trivial and topological excitations

Matthies¹,

Rudner²,

Rosch³

et al. 2022

Preprint

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We propose a simple, robust protocol to prepare a low-energy state of an arbitrary Hamiltonian on a quantum computer or programmable quantum simulator. The protocol is inspired by the adiabatic demagnetization technique, used to cool solid-state systems to extremely low temperatures. A fraction of the qubits (or spins) is used to model a spin bath that is coupled to the system. By an adiabatic ramp down of a simulated Zeeman field acting on the bath spins, energy and entropy are extracted from the system. The bath spins are then measured and reset to the polarized state, and the process is repeated until convergence to a low-energy steady state is achieved. We demonstrate the protocol via application to the quantum Ising model. We study the protocol's performance in the presence of noise and show how the information from the measurement of the bath spins can be used to monitor the cooling process. The performance of the algorithm depends on the nature of the excitations of the system; systems with non-local (topological) excitations are more difficult to cool than those with local excitations. We explore the possible mitigation of this problem by trapping topological excitations.

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Quantum Computing by Coherent Cooling

Cited by 8 publications

References 69 publications

Re-Coherence Generated by Nonlinear Maps

Re-Coherence Generated by Nonlinear Maps

A thermodynamic approach to optimization in complex quantum systems

Programmable adiabatic demagnetization for systems with trivial and topological excitations

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