Gate-based single-shot readout of spins in silicon

West, Anderson; Hensen, B. J.; Jouan, A.; Tanttu, Tuomo; Yang, C. H.; Rossi, Alessandro; González-Zalba, M. Fernando; Hudson, Fay E.; Morello, Andrea; Reilly, David; Dzurak, A. S.

doi:10.1038/s41565-019-0400-7

Cited by 158 publications

(133 citation statements)

References 42 publications

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“…These quantum devices can be implemented in a large number of ways, for example, using ultracold trapped ions [6][7][8][9][10][11], cavity quantum electrodynamics (QED) [12][13][14][15], photonic circuits [16][17][18], silicon quantum dots [19][20][21], and theoretically even by braiding, as yet unobserved, exotic collective excitations called non-abelian anyons [22][23][24]. One of the most promising approaches is using superconducting circuits [25][26][27], where recent advances have resulted in devices consisting of up to 72 qubits, pushing us ever closer to realising so-called quantum supremacy [28].…”

Section: Introductionmentioning

confidence: 99%

Simulating quantum many-body dynamics on a current digital quantum computer

et al. 2019

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Universal quantum computers are potentially an ideal setting for simulating many-body quantum dynamics that is out of reach for classical digital computers. We use state-of-the-art IBM quantum computers to study paradigmatic examples of condensed matter physics -we simulate the effects of disorder and interactions on quantum particle transport, as well as correlation and entanglement spreading. Our benchmark results show that the quality of the current machines is below what is necessary for quantitatively accurate continuous time dynamics of observables and reachable system sizes are small comparable to exact diagonalization. Despite this, we are successfully able to demonstrate clear qualitative behaviour associated with localization physics and many-body interaction effects.IBM is not alone in their efforts to make quantum computing more mainstream, with Microsoft introducing the Q-sharp programming language [53], Google developing the Circq python library [54], and Rigetti providing their own Quantum Cloud Service and Forest SDK built on Python [55]. Rigetti

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Section: Introductionmentioning

confidence: 99%

Simulating quantum many-body dynamics on a current digital quantum computer

et al. 2019

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“…Furthermore, since the drop in visibility in Figure 3 can be attributed to a lower charge readout fidelity owing to the broadening of the SET peak (see Extended Data Figure 9), replacing SET current readout with a readout mechanism that offers better signal to noise ratios should improve readout fidelities at higher temperatures. Radio-frequency gate dispersive readout [9,36] could act as a solution, while, at the same time, providing a truly scalable unit cell footprint.…”

mentioning

confidence: 99%

Operation of a silicon quantum processor unit cell above one kelvin

Yang

Leon

Hwang

et al. 2020

Nature

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285

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Quantum computers are expected to outperform conventional computers for a range of important problems, from molecular simulation to search algorithms, once they can be scaled up to large numbers of quantum bits (qubits), typically millions [1][2][3]. For most solid-state qubit technologies, e.g. those using superconducting circuits or semiconductor spins, scaling poses a significant challenge as every additional qubit increases the heat generated, while the cooling power of dilution refrigerators is severely limited at their operating temperature below 100 mK [4][5][6]. Here we demonstrate operation of a scalable silicon quantum processor unit cell, comprising two qubits confined to quantum dots (QDs) at ∼1.5 Kelvin. We achieve this by isolating the QDs from the electron reservoir, initialising and reading the qubits solely via tunnelling of electrons between the two QDs [7-9]. We coherently control the qubits using electrically-driven spin resonance (EDSR) [10,11] in isotopically enriched silicon 28 Si [12], attaining single-qubit gate fidelities of 98.6% and coherence time T * 2 = 2 µs during 'hot' operation, comparable to those of spin qubits in natural silicon at millikelvin temperatures [13][14][15][16]. Furthermore, we show that the unit cell can be operated at magnetic fields as low as 0.1 T, corresponding to a qubit control frequency of 3.5 GHz, where the qubit energy is well below the thermal energy. The unit cell constitutes the core building block of a full-scale silicon quantum computer, and satisfies layout constraints required by error correction architectures [8,17]. Our work indicates that a spin-based quantum computer could be operated at elevated temperatures in a simple pumped 4 He system, offering orders of magnitude higher cooling power than dilution refrigerators, potentially enabling classical control electronics to be integrated with the qubit array [18,19].Electrostatically gated QDs in Si/SiGe or Si/SiO 2 heterostructures are prime candidates for spin-based quantum computing due to their long coherence times, high control fidelities, and industrial manufacturability [13,14,[20][21][22][23]. In large scale quantum processors the qubits will be arranged in either 1D chains [17] or 2D arrays [3] to enable quantum error correction schemes. For architectures relying on exchange coupling for twoqubit operation [15,16,24,25], the QDs are expected to be densely packed. Until now, two-qubit QD systems have been tunnel-coupled to a nearby charge reservoir that has typically been used for initialisation and readout using spin-to-charge conversion [26]. Here we demonstrate an isolated double QD system that requires no tunnel-coupled reservoir [7-9] to perform full two-qubit initialisation, control and readout -thus realising the elementary unit cell of a scalable quantum processor (see Figure 1h).

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“…All operators appearing in Eq. (17), and in particular σ z , are dressed by the DQD-resonator interaction to first order in g c . Thus, the spin qubit we consider is in fact formed by the states {|−; ↑ , |−; ↓ } dressed by resonator photons.…”

Section: B Effective Spin-qubit Hamiltonianmentioning

confidence: 99%

Optimal dispersive readout of a spin qubit with a microwave resonator

D’Anjou

Burkard

2019

Phys. Rev. B

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Strong coupling of semiconductor spin qubits to superconducting microwave resonators was recently demonstrated [X. Mi et al., Nature 555, 599 (2018); A. J. Landig et al., Nature 560, 179 (2018); N. Samkharadze et al., Science 359, 1123 T. Cubaynes et al., npj Quantum Inf. 5, 47 (2019)]. These breakthroughs pave the way for quantum information processing that combines the long coherence times of solid-state spin qubits with the long-distance connectivity, fast control, and fast high-fidelity quantum-non-demolition readout of existing superconducting qubit implementations. Here, we theoretically analyze and optimize the dispersive readout of a single spin in a semiconductor double quantum dot (DQD) coupled to a microwave resonator via its electric dipole moment. The strong spin-photon coupling arises from the motion of the electron spin in a local magnetic field gradient. We calculate the signal-to-noise ratio (SNR) of the readout accounting for both Purcell spin relaxation and spin relaxation arising from intrinsic electric noise within the semiconductor. We express the maximum achievable SNR in terms of the cooperativity associated with these two dissipation processes. We find that while the cooperativity increases with the strength of the dipole coupling between the DQD and the resonator, it does not depend on the strength of the magnetic field gradient. We then optimize the SNR as a function of experimentally tunable DQD parameters. We identify wide regions of parameter space where the unwanted backaction of the resonator photons on the qubit is small. Moreover, we find that the coupling of the resonator to other DQD transitions can enhance the SNR by at least a factor of two, a "straddling" effect [J. Koch et al., Phys. Rev. A 76, 042319 (2007)] that occurs only at nonzero energy detuning of the DQD double-well potential. We estimate that with current technology, single-shot readout fidelities in the range 82 − 95% can be achieved within a few µs of readout time without requiring the use of Purcell filters. arXiv:1905.09702v2 [cond-mat.mes-hall]

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Gate-based single-shot readout of spins in silicon

Cited by 158 publications

References 42 publications

Simulating quantum many-body dynamics on a current digital quantum computer

Simulating quantum many-body dynamics on a current digital quantum computer

Operation of a silicon quantum processor unit cell above one kelvin

Optimal dispersive readout of a spin qubit with a microwave resonator

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