Four-state discrimination for a pair of spin qubits via gate reflectometry

Abstract

Single-electron spin qubits defined in quantum dots are used as building blocks of a semiconductor-based quantum computer. Readout in a scaled-up version of such a quantum computer is expected to rely on the Pauli Spin Blockade (PSB) mechanism. A desired functionality of PSB readout is that it reveals two bits of information on the two spin qubits that are involved in the process, such that the four computational basis states can be discriminated. In this work, we propose and quantitatively analyze an experimental procedure, based on gate reflectometry, which enables this four-state discrimination in a single measurement. We provide an intuitive recipe to maximize the contrast between the quantum capacitances of the four basis states. Focusing on silicon double quantum dots equipped with a micromagnet, we quantify how amplifier noise and phonon-mediated relaxation influence readout fidelity. Our results highlight a realistic opportunity to mitigate the overhead of readout ancilla qubits in a spin-based quantum computer.

9 pages main text + 8 pages appendix and bibliography

References in corpus (79)

• Quantum Computation with Quantum Dots
• Spins in few-electron quantum dots
• Single-shot read-out of an individual electron spin in a quantum dot
• Driven coherent oscillations of a single electron spin in a quantum dot
• Silicon Quantum Electronics
• Demonstration of Two-Qubit Algorithms with a Superconducting Quantum Processor
• An addressable quantum dot qubit with fault-tolerant control fidelity
• A Two Qubit Logic Gate in Silicon
• A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise
• Semiconductor Spin Qubits
• Electron spin coherence exceeding seconds in high purity silicon
• Storing quantum information for 30 seconds in a nanoelectronic device
• Interfacing spin qubits in quantum dots and donors - hot, dense and coherent
• A CMOS silicon spin qubit
• Electrically driven single electron spin resonance in a slanting Zeeman field
• Computing with spin qubits at the surface code error threshold
• Universal control of a six-qubit quantum processor in silicon
• A four-qubit germanium quantum processor
• Fidelity benchmarks for two-qubit gates in silicon
• Semiconductor Qubits In Practice
• Relaxation, dephasing, and quantum control of electron spins in double quantum dots
• Rapid Single-Shot Measurement of a Singlet-Triplet Qubit
• Fast Single-Charge Sensing with an rf Quantum Point Contact
• Dispersive Readout of a Few-Electron Double Quantum Dot with Fast rf Gate-Sensors
• Fast sensing of double-dot charge arrangement and spin state with an rf sensor quantum dot
• Quantum error correction with silicon spin qubits
• Two-Qubit State Tomography using a Joint Dispersive Read-Out
• Rapid high-fidelity gate-based spin read-out in silicon
• Review of performance metrics of spin qubits in gated semiconducting nanostructures
• Gate-based single-shot readout of spins in silicon
• Gate-reflectometry dispersive readout and coherent control of a spin qubit in silicon
• Probing single electrons across 300 mm spin qubit wafers
• Time-Resolved Detection of Individual Electrons in a Quantum Dot
• Suppression of spin relaxation in an InAs nanowire double quantum dot
• Charge-noise spectroscopy of Si/SiGe quantum dots via dynamically-decoupled exchange oscillations
• Pauli Spin Blockade in the Presence of Strong Spin-Orbit Coupling
• Entanglement Metrology Using a Joint Readout of Superconducting Qubits
• Nagaoka ferromagnetism observed in a quantum dot plaquette
• Electron Transport in Double Quantum Dot governed by Nuclear Magnetic Field
• Probing quantum devices with radio-frequency reflectometry
• Coherent spin qubit transport in silicon
• High-fidelity operation and algorithmic initialisation of spin qubits above one kelvin
• Quantum and Tunnelling Capacitance in Charge and Spin Qubits
• Repetitive single electron spin readout in silicon
• Relaxation of excited spin, orbital, and valley qubit states in single electron silicon quantum dots
• Rapid high-fidelity spin state readout in Si/SiGe quantum dots via radio-frequency reflectometry
• Radio-frequency capacitive gate-based sensing
• Bell's inequality violation with spins in silicon
• The SpinBus Architecture: Scaling Spin Qubits with Electron Shuttling
• High fidelity state preparation, quantum control, and readout of an isotopically enriched silicon spin qubit
• Tomography via Correlation of Noisy Measurement Records
• Spin readout of a CMOS quantum dot by gate reflectometry and spin-dependent tunnelling
• 12-spin-qubit arrays fabricated on a 300 mm semiconductor manufacturing line
• Quantum simulation of antiferromagnetic Heisenberg chain with gate-defined quantum dots
• Universal control of four singlet-triplet qubits
• A 300 mm foundry silicon spin qubit unit cell exceeding 99% fidelity in all operations
• Optimal dispersive readout of a spin qubit with a microwave resonator
• Control of valley dynamics in silicon quantum dots in the presence of an interface step
• Spin-flip phonon-mediated charge relaxation in double quantum dots
• Charge noise and overdrive errors in reflectometry-based charge, spin and Majorana qubit readout
• Small-signal equivalent circuit for double quantum dots at low-frequencies
• Observation of spin-orbit coupling induced Weyl points and topologically protected Kondo effect in a two-electron double quantum dot
• Exciton transport in a germanium quantum dot ladder
• Valley-enhanced fast relaxation of gate-controlled donor qubits in silicon
• Soft Decoding of a Qubit Readout Apparatus
• Classification and magic magnetic-field directions for spin-orbit-coupled double quantum dots
• Robust energy selective tunneling readout of singlet triplet qubits under large magnetic field gradient
• Phonon-assisted relaxation and decoherence of singlet-triplet qubits in Si/SiGe quantum dots
• Pauli spin blockade in CMOS double quantum dot devices
• Magnetic gradient free two axis control of a valley spin qubit in SiGe
• Non-reciprocal Pauli Spin Blockade in a Silicon Double Quantum Dot
• Unified linear response theory of quantum electronic circuits
• Gate-based spin readout of hole quantum dots with site-dependent $g-$factors
• Quantum geometric protocols for fast high-fidelity adiabatic state transfer
• Direct Readout of Nitrogen-Vacancy Hybrid-Spin Quantum Register in Diamond by Photon Arrival Time Analysis
• Operating two exchange-only qubits in parallel
• Compiling the surface code to crossbar spin qubit architectures
• Electrical readout of spins in the absence of spin blockade
• Spin-qubit readout analysis based on a hidden Markov model