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Variational preparation of finite-temperature states on a quantum computer

Journal Article (2021)
Author(s)

Ramiro Sagastizabal (Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre, TU Delft - QCD/DiCarlo Lab)

B. A. Klaver (Kavli institute of nanoscience Delft, Student TU Delft)

M. Adriaan Rol (Kavli institute of nanoscience Delft, TU Delft - QuTech Advanced Research Centre, TU Delft - BUS/Quantum Delft)

V. Negîrneac (Lisbon Technical University, TU Delft - QuTech Advanced Research Centre, TU Delft - BUS/Quantum Delft)

X. Zou (Intel Corporation)

N. Muthusubramanian (TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft, TU Delft - QCD/DiCarlo Lab)

M.C. Beekman (TU Delft - QuTech Advanced Research Centre, TU Delft - BUS/TNO STAFF, TNO)

C. Zachariadis (TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft, TU Delft - QCD/DiCarlo Lab)

Viacheslav Petrovych Ostroukh (TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft, TU Delft - BUS/Quantum Delft)

S.N. Haider (TU Delft - BUS/TNO STAFF, TNO, TU Delft - QuTech Advanced Research Centre)

A Bruno (Kavli institute of nanoscience Delft, TU Delft - BUS/Quantum Delft, TU Delft - QuTech Advanced Research Centre)

L Di Carlo (TU Delft - QuTech Advanced Research Centre, Kavli institute of nanoscience Delft, TU Delft - QN/DiCarlo Lab, TU Delft - QCD/DiCarlo Lab)

More Authors (External organisation)

Research Group
BUS/Quantum Delft
Copyright
© 2021 R.E. Sagastizabal, B. A. Klaver, M.A. Rol, V. Negîrneac, X. Zou, N. Muthusubramanian, M. Beekman, C. Zachariadis, V.P. Ostroukh, S.N. Haider, A. Bruno, L. DiCarlo, More Authors
DOI related publication
https://doi.org/10.1038/s41534-021-00468-1
More Info
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Publication Year
2021
Language
English
Copyright
© 2021 R.E. Sagastizabal, B. A. Klaver, M.A. Rol, V. Negîrneac, X. Zou, N. Muthusubramanian, M. Beekman, C. Zachariadis, V.P. Ostroukh, S.N. Haider, A. Bruno, L. DiCarlo, More Authors
Research Group
BUS/Quantum Delft
Issue number
1
Volume number
7
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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.