skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Characterizing Midcircuit Measurements on a Superconducting Qubit Using Gate Set Tomography

Journal Article · · Physical Review Applied

Measurements that occur within the internal layers of a quantum circuit—midcircuit measurements—are a useful quantum-computing primitive, most notably for quantum error correction. Midcircuit measurements have both classical and quantum outputs, so they can be subject to error modes that do not exist for measurements that terminate quantum circuits. In this work, we show how to characterize midcircuit measurements, modeled by quantum instruments, using a technique that we call quantum instrument linear gate set tomography (QILGST). We then apply this technique to characterize a dispersive measurement on a superconducting transmon qubit within a multiqubit system. By varying the delay time between the measurement pulse and subsequent gates, we explore the impact of residual cavity photon population on measurement error. QILGST can resolve different error modes and quantify the total error from a measurement; in our experiment, for delay times above 1000 ns we measure a total error rate (i.e., half diamond distance) of ϵ$$\diamond$$ = 8.1 ± 1.4%, a readout fidelity of 97.0 ± 0.3%, and output quantum-state fidelities of 96.7 ± 0.6% and 93.7 ± 0.7 % when measuring 0 and 1, respectively.

Research Organization:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
Grant/Contract Number:
NA0003525; 1541959
OSTI ID:
1841992
Report Number(s):
SAND2022-0536J; 702824; TRN: US2301337
Journal Information:
Physical Review Applied, Vol. 17, Issue 1; ISSN 2331-7019
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

References (55)

Entanglement Breaking Channels journal August 2003
Entangling logical qubits with lattice surgery journal January 2021
Towards a heralded eigenstate-preserving measurement of multi-qubit parity in circuit QED journal July 2017
Repeated multi-qubit readout and feedback with a mixed-species trapped-ion register journal November 2018
Self-consistent quantum process tomography journal June 2013
Sequential random access codes and self-testing of quantum measurement instruments journal August 2019
Gate Set Tomography journal October 2021
Detector tomography on IBM quantum computers and mitigation of an imperfect measurement journal November 2019
Error detection on quantum computers improving the accuracy of chemical calculations journal August 2020
Scheme for reducing decoherence in quantum computer memory journal October 1995
Scalable and Robust Randomized Benchmarking of Quantum Processes journal May 2011
Tomography of quantum detectors journal November 2008
Improved Superconducting Qubit Readout by Qubit-Induced Nonlinearities journal September 2010
Effective Fault-Tolerant Quantum Computation with Slow Measurements journal January 2007
Repeat-Until-Success: Non-deterministic decomposition of single-qubit unitaries journal November 2014
Repeated quantum error detection in a surface code journal June 2020
Randomized benchmarking of single- and multi-qubit control in liquid-state NMR quantum information processing journal January 2009
Measuring a transmon qubit in circuit QED: Dressed squeezed states journal July 2016
Demonstration of qubit operations below a rigorous fault tolerance threshold with gate set tomography journal February 2017
Exponential suppression of bit or phase errors with cyclic error correction journal July 2021
Demonstration of Weight-Four Parity Measurements in the Surface Code Architecture journal November 2016
Quantum Process Tomography of a Controlled-NOT Gate journal August 2004
Protecting quantum entanglement from leakage and qubit errors via repetitive parity measurements journal March 2020
Surface codes: Towards practical large-scale quantum computation journal September 2012
Quantum gate teleportation between separated qubits in a trapped-ion processor journal May 2019
High-Fidelity Measurement of Qubits Encoded in Multilevel Superconducting Circuits journal January 2020
Complete Characterization of Arbitrary Quantum Measurement Processes journal November 1999
Fault-tolerant detection of a quantum error journal July 2018
Probing Context-Dependent Errors in Quantum Processors journal June 2019
Real-time processing of stabilizer measurements in a bit-flip code journal August 2020
Device-independent characterization of quantum instruments journal March 2020
The Evolution of Silicon Wafer Cleaning Technology journal January 1990
Efficient Z gates for quantum computing journal August 2017
General method for extracting the quantum efficiency of dispersive qubit readout in circuit QED journal February 2018
Testing quantum fault tolerance on small systems journal November 2018
Noise spectroscopy through dynamical decoupling with a superconducting flux qubit journal May 2011
Hardware for dynamic quantum computing journal October 2017
Quantum computing with realistically noisy devices journal March 2005
Unitary-Feedback-Improved Qubit Initialization in the Dispersive Regime journal November 2015
Probing quantum processor performance with pyGSTi journal July 2020
Cavity quantum electrodynamics for superconducting electrical circuits: An architecture for quantum computation journal June 2004
Semi-device-independent self-testing of unsharp measurements journal July 2020
Bootstrapping quantum process tomography via a perturbative ansatz journal February 2020
Offset masks for lift‐off photoprocessing journal September 1977
Quantum Calibration of Measurement Instrumentation journal December 2004
Nonlinear dispersive regime of cavity QED: The dressed dephasing model journal June 2008
Nature of the Lamb shift in weakly anharmonic atoms: From normal-mode splitting to quantum fluctuations journal November 2018
Complete Characterization of a Quantum Process: The Two-Bit Quantum Gate journal January 1997
Entanglement generated by the dispersive interaction: The dressed coherent state journal January 2016
Implementing and Characterizing Precise Multiqubit Measurements journal September 2016
Prescription for experimental determination of the dynamics of a quantum black box journal November 1997
Resonant Phase Matching of Josephson Junction Traveling Wave Parametric Amplifiers journal October 2014
Detecting and tracking drift in quantum information processors journal October 2020
Tomography of a Feedback Measurement with Photon Detection journal February 2020
Quantum error correction for beginners journal June 2013