Defects in Quantum Computers

The shift of interest from general purpose quantum computers to adiabatic quantum computing or quantum annealing calls for a broadly applicable and easy to implement test to assess how quantum or adiabatic is a specific hardware. Here we propose such a test based on an exactly solvable many body sys...

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Bibliographic Details
Published in:Scientific reports 2018-03, Vol.8 (1), p.4539-10, Article 4539
Main Authors: Gardas, Bartłomiej, Dziarmaga, Jacek, Zurek, Wojciech H., Zwolak, Michael
Format: Article
Language:English
Subjects:
639/766/483/2802
639/766/483/3926
Adiabatic
Atomic and Nuclear Physics
Computers
Defects
Humanities and Social Sciences
MATHEMATICS AND COMPUTING
multidisciplinary
Quantum theory
Science
Science (multidisciplinary)
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Summary:The shift of interest from general purpose quantum computers to adiabatic quantum computing or quantum annealing calls for a broadly applicable and easy to implement test to assess how quantum or adiabatic is a specific hardware. Here we propose such a test based on an exactly solvable many body system–the quantum Ising chain in transverse field–and implement it on the D-Wave machine. An ideal adiabatic quench of the quantum Ising chain should lead to an ordered broken symmetry ground state with all spins aligned in the same direction. An actual quench can be imperfect due to decoherence, noise, flaws in the implemented Hamiltonian, or simply too fast to be adiabatic. Imperfections result in topological defects: Spins change orientation, kinks punctuating ordered sections of the chain. The number of such defects quantifies the extent by which the quantum computer misses the ground state, and is, therefore, imperfect.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-018-22763-2