Protecting quantum entanglement from leakage and qubit errors via repetitive parity measurements

Abstract

Protecting quantum information from errors is essential for large-scale quantum computation. Quantum error correction (QEC) encodes information in entangled states of many qubits, and performs parity measurements to identify errors without destroying the encoded information. However, traditional QEC cannot handle leakage from the qubit computational space. Leakage affects leading experimental platforms, based on trapped ions and superconducting circuits, which use effective qubits within many-level physical systems. We investigate how two-transmon entangled states evolve under repeated parity measurements, and demonstrate the use of hidden Markov models to detect leakage using only the record of parity measurement outcomes required for QEC. We show the stabilization of Bell states over up to 26 parity measurements by mitigating leakage using postselection, and correcting qubit errors using Pauli-frame transformations. Our leakage identification method is computationally efficient and thus compatible with real-time leakage tracking and correction in larger quantum processors.

arXiv comment22 pages, 15 figures

References in corpus (41)

• Surface codes: Towards practical large-scale quantum computation
• Logic gates at the surface code threshold: Superconducting qubits poised for fault-tolerant quantum computing
• Quantum Error Correction for Quantum Memories
• Quantum Computing with Very Noisy Devices
• Demonstration of Two-Qubit Algorithms with a Superconducting Quantum Processor
• State preservation by repetitive error detection in a superconducting quantum circuit
• Fault-tolerant quantum computation with high threshold in two dimensions
• High-fidelity two-qubit quantum logic gates using trapped calcium-43 ions
• High-fidelity quantum logic gates using trapped-ion hyperfine qubits
• High-fidelity preparation, gates, memory and readout of a trapped-ion quantum bit
• Detecting arbitrary quantum errors via stabilizer measurements on a sublattice of the surface code
• Fast Scalable State Measurement with Superconducting Qubits
• Efficient measurement of quantum gate error by interleaved randomized benchmarking
• Deterministic entanglement of superconducting qubits by parity measurement and feedback
• Low-distance Surface Codes under Realistic Quantum Noise
• Demonstration of quantum error correction and universal gate set on a binomial bosonic logical qubit
• Detecting bit-flip errors in a logical qubit using stabilizer measurements
• Rapid high-fidelity multiplexed readout of superconducting qubits
• Experimental demonstration of fault-tolerant state preparation with superconducting qubits
• Fast and Unconditional All-Microwave Reset of a Superconducting Qubit
• Topological Computation without Braiding
• Demonstration of weight-four parity measurements in the surface code architecture
• Scalable quantum circuit and control for a superconducting surface code
• A fast, low-leakage, high-fidelity two-qubit gate for a programmable superconducting quantum computer
• Repeated multi-qubit readout and feedback with a mixed-species trapped-ion register
• Fault-Tolerant Logical Gates in the IBM Quantum Experience
• Rapid Driven Reset of a Qubit Readout Resonator
• 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
• Active resonator reset in the nonlinear dispersive regime of circuit QED
• Comparing and combining measurement-based and driven-dissipative entanglement stabilization
• Quantifying error and leakage in an encoded Si/SiGe triple-dot qubit
• Understanding the effects of leakage in superconducting quantum error detection circuits
• General method for extracting the quantum efficiency of dispersive qubit readout in circuit QED
• Entanglement genesis by ancilla-based parity measurement in 2D circuit QED
• A leakage-resilient approach to fault-tolerant quantum computing with superconducting elements
• Comparing Zeeman qubits to hyperfine qubits in the context of the surface code: ${}^{174}$Yb${}^{+}$ and ${}^{171}$Yb${}^{+}$
• Handling Leakage with Subsystem Codes
• A Silicon Surface Code Architecture Resilient Against Leakage Errors
• What determines the ultimate precision of a quantum computer?

Cited by in corpus (39)

• Realizing Repeated Quantum Error Correction in a Distance-Three Surface Code
• Repeated Quantum Error Detection in a Surface Code
• Engineered Dissipation for Quantum Information Science
• Towards Scalable Bosonic Quantum Error Correction
• Logical-qubit operations in an error-detecting surface code
• 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
• High-contrast ZZ interaction using superconducting qubits with opposite-sign anharmonicity
• Entanglement Stabilization using Parity Detection and Real-Time Feedback in Superconducting Circuits
• Overcoming leakage in scalable quantum error correction
• Rapid and Unconditional Parametric Reset Protocol for Tunable Superconducting Qubits
• Experimental demonstration of continuous quantum error correction
• Mid-circuit measurements on a single species neutral alkali atom quantum processor
• Benchmarking Coherent Errors in Controlled-Phase Gates due to Spectator Qubits
• Dual-rail encoding with superconducting cavities
• Variational preparation of finite-temperature states on a quantum computer
• Leakage detection for a transmon-based surface code
• Experimental exploration of five-qubit quantum error correcting code with superconducting qubits
• Scalable Method for Eliminating Residual $ZZ$ Interaction between Superconducting Qubits
• Suppression of static ZZ interaction in an all-transmon quantum processor
• All-microwave leakage reduction units for quantum error correction with superconducting transmon qubits
• A hardware-efficient leakage-reduction scheme for quantum error correction with superconducting transmon qubits
• Fast Flux-Activated Leakage Reduction for Superconducting Quantum Circuits
• Coupler-Assisted Leakage Reduction for Scalable Quantum Error Correction with Superconducting Qubits
• Experimental error suppression in Cross-Resonance gates via multi-derivative pulse shaping
• Supercurrent parity-meter in a nanowire Cooper-pair transistor
• Generalized figure of merit for qubit readout
• ERASER: Towards Adaptive Leakage Suppression for Fault-Tolerant Quantum Computing
• Improving Quantum Simulation Efficiency of Final State Radiation with Dynamic Quantum Circuits
• Entanglement of a pair of quantum emitters via continuous fluorescence measurements: a tutorial
• Designing fast quantum gates using optimal control with a reinforcement-learning ansatz
• Realizing a Continuous Set of Two-Qubit Gates Parameterized by an Idle Time
• Parametric multi-element coupling architecture for coherent and dissipative control of superconducting qubits
• A practical guide for building superconducting quantum devices
• Error metric for non-trace-preserving quantum operations
• Coherence-Mediated Quantum Thermometry in a Hybrid Circuit-QED Architecture
• Passive leakage removal unit based on a disordered transmon array
• Feedforward suppression of readout-induced faults in quantum error correction
• Logical operations with a dynamical qubit in Floquet-Bacon-Shor code