Variational preparation of finite-temperature states on a quantum computer

R. Sagastizabal; B. A. Klaver; M. A. Rol; V. Negîrneac; X. Zou; N. Muthusubramanian; M. Beekman; C. Zachariadis; V. P. Ostroukh; N. Haider; A. Bruno; L. DiCarlo; null More Authors

doi:10.1038/s41534-021-00468-1

Variational preparation of finite-temperature states on a quantum computer

R. Sagastizabal, B. A. Klaver, M. A. Rol, V. Negîrneac, X. Zou, N. Muthusubramanian, M. Beekman, C. Zachariadis, V. P. Ostroukh, N. Haider, A. Bruno, L. DiCarlo^*, More Authors

^*Corresponding author for this work

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Abstract

The preparation of thermal equilibrium states is important for the simulation of condensed matter and cosmology systems using a quantum computer. We present a method to prepare such mixed states with unitary operators and demonstrate this technique experimentally using a gate-based quantum processor. Our method targets the generation of thermofield double states using a hybrid quantum-classical variational approach motivated by quantum-approximate optimization algorithms, without prior calculation of optimal variational parameters by numerical simulation. The fidelity of generated states to the thermal-equilibrium state smoothly varies from 99 to 75% between infinite and near-zero simulated temperature, in quantitative agreement with numerical simulations of the noisy quantum processor with error parameters drawn from experiment.

Original language	English
Article number	130
Number of pages	7
Journal	NPJ Quantum Information
Volume	7
Issue number	1
DOIs	https://doi.org/10.1038/s41534-021-00468-1
Publication status	Published - 2021

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s41534-021-00468-1Final published version, 2.42 MBLicence: CC BY

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title = "Variational preparation of finite-temperature states on a quantum computer",

abstract = "The preparation of thermal equilibrium states is important for the simulation of condensed matter and cosmology systems using a quantum computer. We present a method to prepare such mixed states with unitary operators and demonstrate this technique experimentally using a gate-based quantum processor. Our method targets the generation of thermofield double states using a hybrid quantum-classical variational approach motivated by quantum-approximate optimization algorithms, without prior calculation of optimal variational parameters by numerical simulation. The fidelity of generated states to the thermal-equilibrium state smoothly varies from 99 to 75% between infinite and near-zero simulated temperature, in quantitative agreement with numerical simulations of the noisy quantum processor with error parameters drawn from experiment.",

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T1 - Variational preparation of finite-temperature states on a quantum computer

AU - Sagastizabal, R.

AU - Klaver, B. A.

AU - Rol, M. A.

AU - Negîrneac, V.

AU - Zou, X.

AU - Muthusubramanian, N.

AU - Beekman, M.

AU - Zachariadis, C.

AU - Ostroukh, V. P.

AU - Haider, N.

AU - Bruno, A.

AU - DiCarlo, L.

AU - More Authors, null

PY - 2021

Y1 - 2021

N2 - The preparation of thermal equilibrium states is important for the simulation of condensed matter and cosmology systems using a quantum computer. We present a method to prepare such mixed states with unitary operators and demonstrate this technique experimentally using a gate-based quantum processor. Our method targets the generation of thermofield double states using a hybrid quantum-classical variational approach motivated by quantum-approximate optimization algorithms, without prior calculation of optimal variational parameters by numerical simulation. The fidelity of generated states to the thermal-equilibrium state smoothly varies from 99 to 75% between infinite and near-zero simulated temperature, in quantitative agreement with numerical simulations of the noisy quantum processor with error parameters drawn from experiment.

AB - The preparation of thermal equilibrium states is important for the simulation of condensed matter and cosmology systems using a quantum computer. We present a method to prepare such mixed states with unitary operators and demonstrate this technique experimentally using a gate-based quantum processor. Our method targets the generation of thermofield double states using a hybrid quantum-classical variational approach motivated by quantum-approximate optimization algorithms, without prior calculation of optimal variational parameters by numerical simulation. The fidelity of generated states to the thermal-equilibrium state smoothly varies from 99 to 75% between infinite and near-zero simulated temperature, in quantitative agreement with numerical simulations of the noisy quantum processor with error parameters drawn from experiment.

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DO - 10.1038/s41534-021-00468-1

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SN - 2056-6387

VL - 7

JO - NPJ Quantum Information

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Variational preparation of finite-temperature states on a quantum computer

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