A hardware-efficient leakage-reduction scheme for quantum error correction with superconducting transmon qubits

Abstract

Leakage outside of the qubit computational subspace poses a threatening challenge to quantum error correction (QEC). We propose a scheme using two leakage-reduction units (LRUs) that mitigate these issues for a transmon-based surface code, without requiring an overhead in terms of hardware or QEC-cycle time as in previous proposals. For data qubits we consider a microwave drive to transfer leakage to the readout resonator, where it quickly decays, ensuring that this negligibly affects the coherence within the computational subspace for realistic system parameters. For ancilla qubits we apply a $|1⟩\leftrightarrow |2⟩$ $\pi$ pulse conditioned on the measurement outcome. Using density-matrix simulations of the distance-3 surface code we show that the average leakage lifetime is reduced to almost 1 QEC cycle, even when the LRUs are implemented with limited fidelity. Furthermore, we show that this leads to a significant reduction of the logical error rate. This LRU scheme opens the prospect for near-term scalable QEC demonstrations.

References in corpus (56)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• Surface codes: Towards practical large-scale quantum computation
• Quantum computational advantage using photons
• Logic gates at the surface code threshold: Superconducting qubits poised for fault-tolerant quantum computing
• Demonstration of Two-Qubit Algorithms with a Superconducting Quantum Processor
• State preservation by repetitive error detection in a superconducting quantum circuit
• Hartree-Fock on a superconducting qubit quantum computer
• High-fidelity preparation, gates, memory and readout of a trapped-ion quantum bit
• Schrieffer-Wolff transformation for quantum many-body systems
• Procedure for systematically tuning up crosstalk in the cross resonance gate
• Fast Scalable State Measurement with Superconducting Qubits
• A tunable coupling scheme for implementing high-fidelity two-qubit gates
• Quantum advantage with shallow circuits
• Repeated Quantum Error Detection in a Surface Code
• Demonstrating a Continuous Set of Two-qubit Gates for Near-term Quantum Algorithms
• Dispersive regime of circuit QED: photon-dependent qubit dephasing and relaxation rates
• Detecting bit-flip errors in a logical qubit using stabilizer measurements
• Rapid high-fidelity multiplexed readout of superconducting qubits
• Measuring and Suppressing Quantum State Leakage in a Superconducting Qubit
• Realization of high-fidelity CZ and ZZ-free iSWAP gates with a tunable coupler
• Fast and Unconditional All-Microwave Reset of a Superconducting Qubit
• Quantum logic gates for coupled superconducting phase qubits
• Effective Hamiltonian models of the cross-resonance gate
• Feedback control of a solid-state qubit using high-fidelity projective measurement
• Demonstration of weight-four parity measurements in the surface code architecture
• Scalable quantum circuit and control for a superconducting surface code
• Fast adiabatic qubit gates using only ${\sigma }_z$ control
• Quantification and Characterization of Leakage Errors
• A fast, low-leakage, high-fidelity two-qubit gate for a programmable superconducting quantum computer
• Focus beyond quadratic speedups for error-corrected quantum advantage
• Repeated multi-qubit readout and feedback with a mixed-species trapped-ion register
• Removing leakage-induced correlated errors in superconducting quantum error correction
• High-fidelity controlled-Z gate with maximal intermediate leakage operating at the speed limit in a superconducting quantum processor
• Operation and intrinsic error budget of a two-qubit cross-resonance gate
• Microwave-Induced Amplitude and Phase Tunable Qubit-Resonator Coupling in Circuit Quantum Electrodynamics
• Coping with qubit leakage in topological codes
• Density-matrix simulation of small surface codes under current and projected experimental noise
• Entanglement Stabilization using Parity Detection and Real-Time Feedback in Superconducting Circuits
• Error Correction and Degeneracy in Surface Codes Suffering Loss
• Active resonator reset in the nonlinear dispersive regime of circuit QED
• Restless Tuneup of High-Fidelity Qubit Gates
• Demonstration of a Parametrically-Activated Entangling Gate Protected from Flux Noise
• Benchmarking Coherent Errors in Controlled-Phase Gates due to Spectator Qubits
• Pulsed reset protocol for fixed-frequency superconducting qubits
• Understanding the effects of leakage in superconducting quantum error detection circuits
• Protecting quantum entanglement from leakage and qubit errors via repetitive parity measurements
• Leakage detection for a transmon-based surface code
• Fault-tolerance thresholds for the surface code with fabrication errors
• A leakage-resilient approach to fault-tolerant quantum computing with superconducting elements
• Surface Code Error Correction on a Defective Lattice
• Eliminating Leakage Errors in Hyperfine Qubits
• Comparing Zeeman qubits to hyperfine qubits in the context of the surface code: ${}^{174}$Yb${}^{+}$ and ${}^{171}$Yb${}^{+}$
• Handling Leakage with Subsystem Codes
• Leakage mitigation for quantum error correction using a mixed qubit scheme
• Adaptive weight estimator for quantum error correction
• State leakage during fast decay and control of a superconducting transmon qubit

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• Overcoming leakage in scalable quantum error correction
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• Real-Time Decoding for Fault-Tolerant Quantum Computing: Progress, Challenges and Outlook
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• High-performance repetition cat code using fast noisy operations
• Optimization of decoder priors for accurate quantum error correction
• Multi-Purpose Architecture for Fast Reset and Protective Readout of Superconducting Qubits
• Detrimental non-Markovian errors for surface code memory
• Surface Code with Imperfect Erasure Checks
• Quantum State Transfer via a Multimode Resonator
• Parametric multi-element coupling architecture for coherent and dissipative control of superconducting qubits
• Realizing a Continuous Set of Two-Qubit Gates Parameterized by an Idle Time
• Precise certification of a qubit space
• Balanced cross-Kerr coupling for superconducting qubit readout
• Leakage in restless quantum gate calibration
• Multimode Purcell Filter for Superconducting-Qubit Reset and Readout with Intrinsic Purcell Protection
• Error metric for non-trace-preserving quantum operations
• Leakage Mobility in Superconducting Qubits as a Leakage Reduction Unit
• Accurate Leakage Speculation for Quantum Error Correction
• Geometric Phase of a Transmon in a Dissipative Quantum Circuit
• Feedforward suppression of readout-induced faults in quantum error correction
• Incoherent Approximation of Leakage in Quantum Error Correction
• Passive leakage removal unit based on a disordered transmon array
• Mitigating errors in state preparation and measurement with noncomputational states