Quantifying error and leakage in an encoded Si/SiGe triple-dot qubit

Abstract

Quantum computation requires qubits that satisfy often-conflicting criteria, including scalable control and long-lasting coherence. One approach to creating a suitable qubit is to operate in an encoded subspace of several physical qubits. Though such encoded qubits may be particularly susceptible to leakage out of their computational subspace, they can be insensitive to certain noise processes and can also allow logical control with a single type of entangling interaction while maintaining favorable features of the underlying physical system. Here we demonstrate a qubit encoded in a subsystem of three coupled electron spins confined in gated, isotopically enhanced silicon quantum dots. Using a modified "blind" randomized benchmarking protocol that determines both computational and leakage errors, we show that unitary operations have an average total error of 0.35%, with 0.17% of that coming from leakage driven by interactions with substrate nuclear spins. This demonstration utilizes only the voltage-controlled exchange interaction for qubit manipulation and highlights the operational benefits of encoded subsystems, heralding the realization of high-quality encoded multi-qubit operations.

arXiv comment15 pages, 6 figures

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Cited by in corpus (55)

• Semiconductor Spin Qubits
• Qubits made by advanced semiconductor manufacturing
• Review of performance metrics of spin qubits in gated semiconducting nanostructures
• Low-frequency spin qubit detuning noise in highly purified ${}^{28}$Si/SiGe
• Universal logic with encoded spin qubits in silicon
• Quantum tomography of an entangled three-spin state in silicon
• Radio-frequency detected fast charge sensing in undoped silicon quantum dots
• Single-electron control in a foundry-fabricated two-dimensional qubit array
• Calibrated decoders for experimental quantum error correction
• Simultaneous single-qubit driving of semiconductor spin qubits at the fault-tolerant threshold
• Operating semiconductor quantum processors with hopping spins
• Resonantly driven singlet-triplet spin qubit in silicon
• Closed-loop control of a GaAs-based singlet-triplet spin qubit with 99.5% gate fidelity and low leakage
• A flexible design platform for Si/SiGe exchange-only qubits with low disorder
• Probing quantum processor performance with pyGSTi
• Protecting quantum entanglement from leakage and qubit errors via repetitive parity measurements
• High fidelity state preparation, quantum control, and readout of an isotopically enriched silicon spin qubit
• Fast and high-fidelity state preparation and measurement in triple-quantum-dot spin qubits
• Coherent long-distance spin-qubit-transmon coupling
• Strong electron-electron interactions in Si/SiGe quantum dots
• Detuning Axis Pulsed Spectroscopy of Valley-Orbital States in Si/SiGe Quantum Dots
• Dissipative preparation of W states in trapped ion systems
• Universal non-adiabatic control of small-gap superconducting qubits
• Controllable freezing of the nuclear spin bath in a single-atom spin qubit
• How valley-orbit states in silicon quantum dots probe quantum well interfaces
• Subspace benchmarking high-fidelity entangling operations with trapped ions
• Coherent spin-valley oscillations in silicon
• Character randomized benchmarking for non-multiplicity-free groups with applications to subspace, leakage, and matchgate randomized benchmarking
• Spin digitizer for high-fidelity readout of a cavity-coupled silicon triple quantum dot
• Two-body Wigner molecularization in asymmetric quantum dot spin qubits
• Learning correlated noise in a 39-qubit quantum processor
• Magnetic Gradient Fluctuations from Quadrupolar ${}^{73}$Ge in Si/SiGe Exchange-Only Qubits
• Probing the Spatial Variation of the Inter-Valley Tunnel Coupling in a Silicon Triple Quantum Dot
• Fast Flux-Activated Leakage Reduction for Superconducting Quantum Circuits
• Resonant Exchange Operation in Triple-Quantum-Dot Qubits for Spin-Photon Transduction
• Realization of a $C{Q}_3$ Qubit: energy spectroscopy and coherence
• A Practical Introduction to Benchmarking and Characterization of Quantum Computers
• Highly tunable exchange-only singlet-only qubit in a GaAs triple quantum dot
• Cryogen-free scanning gate microscope for the characterization of Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices at milli-Kelvin temperatures
• Coherent control of a triangular exchange-only spin qubit
• Optimizing Stabilizer Parities for Improved Logical Qubit Memories
• Anisotropic $g$-tensors in hole quantum dots: The role of the transverse confinement direction
• Optimization of Quantum-dot Qubit Fabrication via Machine Learning
• Analytical percolation theory for topological color codes under qubit loss
• Efficient Two-Qubit Pulse Sequences Beyond CNOT
• Hybrid Exchange Measurement-Based Qubit Operations in Semiconductor Double Quantum Dot Qubits
• Randomized Benchmarking with Leakage Errors
• Operating two exchange-only qubits in parallel
• Leakage Benchmarking for Universal Gate Sets
• Single-shot latched readout of a quantum dot qubit using barrier gate pulsing
• Correcting on-chip distortion of control pulses with silicon spin qubits
• Error metric for non-trace-preserving quantum operations
• Singlet-only Always-on Gapless Exchange Qubits with Baseband Control
• Hardware-efficient random circuits to classify noise in a multi-qubit system
• Jenga-Krotov algorithm: Efficient compilation of multi-qubit gates for exchange-only qubits