Spin Digitizer for High-Fidelity Readout of a Cavity-Coupled Silicon Triple Quantum Dot

Borjans, Felix; Mi, Xiao; Petta, J. R.

doi:10.1103/physrevapplied.15.044052

Cited by 29 publications

(19 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Further increasing F I to 99.9% will be possible by adopting faster readout techniques, e.g. with cold baseband [47] or radiofrequency [48,49] amplifiers, or in cavity-based setups [50][51][52][53].…”

Section: Discussionmentioning

confidence: 99%

Beating the thermal limit of qubit initialization with a Bayesian Maxwell's demon

Johnson¹,

Mądzik²,

Hudson³

et al. 2021

Preprint

View full text Add to dashboard Cite

Fault-tolerant quantum computing requires initializing the quantum register in a well-defined fiducial state. In solid-state systems, this is typically achieved through thermalization to a cold reservoir, such that the initialization fidelity is fundamentally limited by temperature. Here we present a method of preparing a fiducial quantum state that beats the thermal limit. It is based on real-time monitoring of the qubit through a negative-result measurement -the equivalent of a 'Maxwell's demon' that only triggers the experiment upon the appearance of a very cold qubit. We experimentally apply it to initialize an electron spin qubit in silicon, achieving a ground-state initialization fidelity of 98.9(4)%, a ≈ 19% improvement over the intrinsic fidelity of the system. A fidelity approaching 99.9% could be achieved with realistic improvements in the bandwidth of the amplifier chain or by slowing down the rate of electron tunneling from the reservoir. We use a nuclear spin ancilla, measured in quantum nondemolition mode, to prove the value of the electron initialization fidelity far beyond the intrinsic fidelity of the electron readout. However, the method itself does not require an ancilla for its execution, saving the need for additional resources. The quantitative analysis of the initialization fidelity reveals that a simple picture of spin-dependent electron tunneling does not correctly describe the data. Our digital 'Maxwell's demon' can be applied to a wide range of quantum systems, with minimal demands on control and detection hardware.

show abstract

Section: Discussionmentioning

confidence: 99%

Beating the thermal limit of qubit initialization with a Bayesian Maxwell's demon

Johnson¹,

Mądzik²,

Hudson³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…3 (a) indicates the region within which V M is large enough to shift the SLQD1 Coulomb peak from full signal (on top of the peak) to < 1% signal due to a charging event on the target qubit (the strong response threshold). Any qubit located inside the footprint of this contour would generate full on-off switching of the sensor signal [14], and could be measured without any loss of fidelity due to the distance from the sensor.…”

Section: Single-shot Spin Readoutmentioning

confidence: 99%

“…This frequency-domain method for determining the charge sensitivity in e/ √ Hz is scaled to the charging energy of the sensor (which can vary significantly between devices and different material systems) and hence cannot be directly compared between different experiments. This method also only quantifies the response of the sensor to small charge shifts (much smaller than the Coulomb peak linewidth), and is hence an inappropriate metric for strong-response regime charge sensors (where the sensor signal shifts by an appreciable fraction of a linewidth due to a charging event on a nearby qubit) [5,14,16,17,19]. Because it is scaled to the sensor charging energy, this frequency domain method is also unsuitable for sensors which do not have a periodic response in the gate charge, such as direct dispersive sensors measuring inter-dot transitions.…”

Section: Device Fabricationmentioning

confidence: 99%

“…In contrast gate-based (or dispersive) sensors integrate qubit readout capability into the existing leads used for qubit control, allowing spin measurements without additional proximal charge sensors [6][7][8][9]. Single-shot readout using dispersive sensors has recently been demonstrated [10][11][12][13][14], however these results relied on Pauli blockade between two spins for readout, requiring an additional quantum dot (with associated control leads) for spin detection. Furthermore, in each case readout of only a single qubit was achieved.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Single-shot readout of multiple donor electron spins with a gate-based sensor

Hogg¹,

Pakkiam²,

Gorman³

et al. 2022

Preprint

View full text Add to dashboard Cite

Proposals for large-scale semiconductor spin-based quantum computers require high-fidelity singleshot qubit readout to perform error correction and read out qubit registers at the end of a computation. However, as devices scale to larger qubit numbers integrating readout sensors into densely packed qubit chips is a critical challenge. Two promising approaches are minimising the footprint of the sensors, and extending the range of each sensor to read more qubits. Here we show high-fidelity single-shot electron spin readout using a nanoscale single-lead quantum dot (SLQD) sensor that is both compact and capable of reading multiple qubits. Our gate-based SLQD sensor is deployed in an all-epitaxial silicon donor spin qubit device, and we demonstrate single-shot readout of three 31 P donor quantum dot electron spins with a maximum fidelity of 95%. Importantly in our device the quantum dot confinement potentials are provided inherently by the donors, removing the need for additional metallic confinement gates and resulting in strong capacitive interactions between sensor and donor quantum dots. We observe a 1/d 1.4 scaling of the capacitive coupling between sensor and 31 P dots (where d is the sensor-dot distance), compared to 1/d 2.5−3.0 in gate-defined quantum dot devices. Due to the small qubit size and strong capacitive interactions in all-epitaxial donor devices, we estimate a single sensor can achieve single-shot readout of approximately 15 qubits in a linear array, compared to 3-4 qubits for a similar sensor in a gate-defined quantum dot device. Our results highlight the potential for spin qubit devices with significantly reduced sensor densities.

show abstract

“…The SEB, however, offers the key technological advantage it can detect electronic transitions occurring at rates much lower than the probing rf frequency, a common necessity in the few-electron regime where qubits are operated. However, the performance of SEBs in silicon has remained non-competitive with respect to SETs (99.2% in 100 µs [22]), raising the question of whether fast and compact high-fidelity readout could be possible.…”

mentioning

confidence: 99%

Fast high-fidelity single-shot readout of spins in silicon using a single-electron box

A.¹,

Ciriano-Tejel²,

Wise³

et al. 2022

Preprint

View full text Add to dashboard Cite

Spin Digitizer for High-Fidelity Readout of a Cavity-Coupled Silicon Triple Quantum Dot

Cited by 29 publications

References 39 publications

Beating the thermal limit of qubit initialization with a Bayesian Maxwell's demon

Beating the thermal limit of qubit initialization with a Bayesian Maxwell's demon

Single-shot readout of multiple donor electron spins with a gate-based sensor

Fast high-fidelity single-shot readout of spins in silicon using a single-electron box

Contact Info

Product

Resources

About