Fast, Lifetime-Preserving Readout for High-Coherence Quantum Annealers
- URL: http://arxiv.org/abs/2006.10817v2
- Date: Thu, 19 Nov 2020 21:27:23 GMT
- Title: Fast, Lifetime-Preserving Readout for High-Coherence Quantum Annealers
- Authors: Jeffrey A. Grover, James I. Basham, Alexander Marakov, Steven M.
Disseler, Robert T. Hinkey, Moe Khalil, Zachary A. Stegen, Thomas Chamberlin,
Wade DeGottardi, David J. Clarke, James R. Medford, Joel D. Strand, Micah J.
A. Stoutimore, Sergey Novikov, David G. Ferguson, Daniel Lidar, Kenneth M.
Zick, Anthony J. Przybysz
- Abstract summary: We show that a quantum flux parametron (QFP) is capable of acting as both isolator and amplifier in the readout circuit of a capacitively shunted flux qubit (CSFQ)
The device is shown to read out a flux qubit in the persistent current basis with fidelities surpassing $98.6%$ with only $80$ ns integration, and reaches fidelities of $99.6%$ when integrated for $1$ $mu$s.
- Score: 38.98439939494304
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: We demonstrate, for the first time, that a quantum flux parametron (QFP) is
capable of acting as both isolator and amplifier in the readout circuit of a
capacitively shunted flux qubit (CSFQ). By treating the QFP like a tunable
coupler and biasing it such that the coupling is off, we show that $T_1$ of the
CSFQ is not impacted by Purcell loss from its low-Q readout resonator ($Q_e =
760$) despite being detuned by only $40$ MHz. When annealed, the QFP amplifies
the qubit's persistent current signal such that it generates a flux
qubit-state-dependent frequency shift of $85$ MHz in the readout resonator,
which is over $9$ times its linewidth. The device is shown to read out a flux
qubit in the persistent current basis with fidelities surpassing $98.6\%$ with
only $80$ ns integration, and reaches fidelities of $99.6\%$ when integrated
for $1$ $\mu$s. This combination of speed and isolation is critical to the
readout of high-coherence quantum annealers.
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