Electrometry Using Coherent Exchange Oscillations in a Singlet-Triplet-Qubit

Abstract

Two level systems that can be reliably controlled and measured hold promise in both metrology and as qubits for quantum information science (QIS). When prepared in a superposition of two states and allowed to evolve freely, the state of the system precesses with a frequency proportional to the splitting between the states. In QIS,this precession forms the basis for universal control of the qubit,and in metrology the frequency of the precession provides a sensitive measurement of the splitting. However, on a timescale of the coherence time, $T_2$, the qubit loses its quantum information due to interactions with its noisy environment, causing qubit oscillations to decay and setting a limit on the fidelity of quantum control and the precision of qubit-based measurements. Understanding how the qubit couples to its environment and the dynamics of the noise in the environment are therefore key to effective QIS experiments and metrology. Here we show measurements of the level splitting and dephasing due to voltage noise of a GaAs singlet-triplet qubit during exchange oscillations. Using free evolution and Hahn echo experiments we probe the low frequency and high frequency environmental fluctuations, respectively. The measured fluctuations at high frequencies are small, allowing the qubit to be used as a charge sensor with a sensitivity of $2\times 10^{-8}e/\sqrt{\mathrm{Hz}}$, two orders of magnitude better than the quantum limit for an RF single electron transistor (RF-SET). We find that the dephasing is due to non-Markovian voltage fluctuations in both regimes and exhibits an unexpected temperature dependence. Based on these measurements we provide recommendations for improving $T_2$ in future experiments, allowing for higher fidelity operations and improved charge sensitivity.

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• Coupling of three-spin qubits to their electric environment
• Exchange-based two-qubit gate for singlet-triplet qubits
• Negative spin exchange in a multielectron quantum dot
• The asymmetric resonant exchange qubit under the influence of electrical noise
• Open quantum system description of singlet-triplet qubits in quantum dots
• Crosstalk error correction through dynamical decoupling of single-qubit gates in capacitively coupled singlet-triplet semiconductor spin qubits
• Microscopic models for charge-noise-induced dephasing of solid-state qubits
• Adiabatic electron charge transfer between two quantum dots in presence of 1/f noise
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• Decoherence of a Driven Qubit
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• Single-spin manipulation in a double quantum dot in the field of a micromagnet
• Two-Qubit Pulse Gate for the Three-Electron Double Quantum Dot Qubit
• Noise-compensating pulses for electrostatically controlled silicon spin qubits
• Environmental noise effects on entanglement fidelity of exchange-coupled semiconductor spin qubits
• Intrinsic decoherence in isolated quantum systems
• Dynamics of entanglement of two electron spins interacting with nuclear spin baths in quantum dots
• Fast pulse sequences for dynamically corrected gates in single-triplet qubits
• High-Fidelity Entangling Gates for Quantum-Dot Hybrid Qubits Based on Exchange Interactions
• Transfer of a quantum state from a photonic qubit to a gate-defined quantum dot
• Fabrication and characterization of an undoped GaAs/AlGaAs quantum dot device
• Validity of the single-particle description and charge noise resilience for multielectron quantum dots
• High Fidelity Singlet-Triplet $S$-$T_{-}$ Qubits in Inhomogeneous Magnetic Fields
• Charge-noise tolerant exchange gates of singlet-triplet qubits in asymmetric double quantum dots
• Inverted Singlet-Triplet Qubit Coded on a Two-Electron Double Quantum Dot
• Nonequilibrium-induced enhancement of dynamical quantum coherence and entanglement of spin arrays
• Extended orbital modeling of spin qubits in double quantum dots
• Low-temperature environments for quantum computation and quantum simulation
• Black holes as Andreev reflecting mirrors
• 1/f noise in quantum nanoscience
• Field-effect-induced two-dimensional electron gas utilizing modulation doping for improved ohmic contacts
• Capacitative coupling of singlet-triplet qubits in different inter-qubit geometries
• Localization of a magnetic moment using a two-qubit probe
• A robust operating point for capacitively coupled singlet-triplet qubits
• Electron spin-flip correlations due to nuclear dynamics in driven GaAs double dots
• Conditioned spin and charge dynamics of a single electron quantum dot
• In-flight detection of few electrons using a singlet-triplet spin qubit
• Qubit decoherence under two-axis coupling to low-frequency noises
• Landau-Zener Transitions in Spin Qubit Encoded in Three Quantum Dots