Loading a quantum-dot based “Qubyte” register

Volk, Christian; Zwerver, Anne-Marije; Mukhopadhyay, U.; Eendebak, Pieter; Diepen, C. J. van; Dehollain, Juan Pablo; Hensgens, Toivo; Fujita, Takafumi; Reichl, Christian; Wegscheider, Werner; Vandersypen, L. M. K.

doi:10.1038/s41534-019-0146-y

Cited by 103 publications

(88 citation statements)

References 37 publications

(42 reference statements)

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“…For the experimental implementation, scalable QD arrays of increasing size have been recently fabricated [50,51], making our proposal feasible with state of the art techniques.…”

Section: Discussionmentioning

confidence: 99%

Simulation of 1D Topological Phases in Driven Quantum Dot Arrays

et al. 2019

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We propose a driving protocol which allows to use quantum dot arrays as quantum simulators for 1D topological phases. We show that by driving the system out of equilibrium, one can imprint bond-order in the lattice (producing structures such as dimers, trimers, etc) and selectively modify the hopping amplitudes at will. Our driving protocol also allows for the simultaneous suppression of all the undesired hopping processes and the enhancement of the necessary ones, enforcing certain key symmetries which provide topological protection. In addition, we have discussed its implementation in a 12-QD array with two interacting electrons and found correlation effects in their dynamics, when configurations with different number of edge states are considered.

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“…For the experimental implementation, scalable QD arrays of increasing size have been recently fabricated [50,51], making our proposal feasible with state of the art techniques.…”

Section: Discussionmentioning

confidence: 99%

Simulation of 1D Topological Phases in Driven Quantum Dot Arrays

et al. 2019

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“…Virtual gates have been described in detail and compensate for the effects of device cross-capacitance through software corrections that effectively invert the capacitance matrix [21,[30][31][32][33]. Whenever the voltage of gate V P i is adjusted to tune the chemical potential of dot i, the voltages on adjacent gates V P (i−1) and V P (i+1) are modified by a calibrated amount to keep the chemical potentials of dots i − 1 and i + 1 constant.…”

mentioning

confidence: 99%

Site-Selective Quantum Control in an Isotopically Enriched Si28/Si0.7Ge0.3 Quadruple Quantum Dot

et al. 2019

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Silicon spin qubits are a promising quantum computing platform offering long coherence times, small device sizes, and compatibility with industry-backed device fabrication techniques. In recent years, high fidelity single-qubit and two-qubit operations have been demonstrated in Si. Here, we demonstrate coherent spin control in a quadruple quantum dot fabricated using isotopically enriched 28 Si. We tune the ground state charge configuration of the quadruple dot down to the single electron regime and demonstrate tunable interdot tunnel couplings as large as 20 GHz, which enables exchange-based two-qubit gate operations. Site-selective single spin rotations are achieved using electric dipole spin resonance in a magnetic field gradient. We execute a resonant-CNOT gate between two adjacent spins in 270 ns.Quantum processors based on spins in semiconductors [1-3] are rapidly becoming a strong contender in the global race to build a quantum cofmputer. In particular, silicon is an excellent host material for spin-based quantum computing by virtue of its small spin-orbit coupling and long spin coherence times [4,5]. Within the past few years, tremendous progress has been made in achieving high fidelity single-qubit [6, 7] and two-qubit control [8][9][10][11][12] in silicon. Scalable one-dimensional arrays of silicon quantum dots have been demonstrated [13], and in GaAs, where electron wavefunctions are comparably large, both one-[14-16] and two-dimensional arrays [17,18] of spins have been fabricated. Despite this progress, quantum control of spins in silicon has been limited to one-and two-qubit devices. Scaling beyond two-qubit devices opens the door to important experiments which are currently out of reach, including error correction [19,20], quantum simulation [21][22][23][24], and demonstrations of time crystal phases [25].In this Letter, we demonstrate operation of a fourqubit device fabricated using an isotopically enriched 28 Si/SiGe heterostructure. The device offers independent control of all four qubits, as well as pairwise two-qubit gates mediated by the exchange interaction [26]. We demonstrate control and measurement of the charge state of the array, and operate in the regime where each dot contains only one electron. We perform electric dipole spin resonance (EDSR) spectroscopy on all four qubits to show that they have unique spin resonance frequencies. Finally, we modulate the tunnel coupling between adjacent dots and demonstrate a resonant-CNOT gate [9,27].Four spin qubits are arranged in a linear array using an overlapping gate architecture, as shown in Fig. 1(a) [28]. Single spin qubits are formed by accumulating a electron under each plunger gate: P 1 , P 2 , P 3 , and P 4 . The couplings between dots and between dots and the charge reservoirs formed beneath gates S 3 and D 3 are tuned by adjusting the barrier gate voltages V Bi . Charge sensing is performed by monitoring the currents I S1 and I S2 through two proximal quantum dot charge detectors TS 800 600 650 850 V P4 (mV) 640 700 800 Dot 4 V P1 (m...

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“…Details of the fabrication and characterization of a nominally identical device are described in Ref. [13]. Quantum dots are formed by applying DC voltages to a set of plunger gates, P, and barrier gates, B.…”

Section: A Quadruple Quantum Dot Devicementioning

confidence: 99%

“…The virtual gates are obtained by inverting a crosstalk matrix that expresses by how much each physical gate shifts each of the electrochemical potentials. The technique of crosstalk compensation for dot potentials has become a standard and essential technique in multidot experiments [13][14][15]. However, the interdot tunnel coupling is approximately an exponential function of the gate voltages [10,16,17], and so far it has remained unclear how to incorporate this nonlinear dependence into the crosstalk matrix.…”

Section: Introductionmentioning

confidence: 99%

Efficient Orthogonal Control of Tunnel Couplings in a Quantum Dot Array

et al. 2020

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Electrostatically-defined semiconductor quantum dot arrays offer a promising platform for quantum computation and quantum simulation. However, crosstalk of gate voltages to dot potentials and interdot tunnel couplings complicates the tuning of the device parameters. To date, crosstalk to the dot potentials is routinely and efficiently compensated using so-called virtual gates, which are specific linear combinations of physical gate voltages. However, due to exponential dependence of tunnel couplings on gate voltages, crosstalk to the tunnel barriers is currently compensated through a slow iterative process. In this work, we show that the crosstalk on tunnel barriers can be efficiently characterized and compensated for, using the fact that the same exponential dependence applies to all gates. We demonstrate efficient calibration of crosstalk in a quadruple quantum dot array and define a set of virtual barrier gates, with which we show orthogonal control of all interdot tunnel couplings. Our method marks a key step forward in the scalability of the tuning process of large-scale quantum dot arrays.

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Loading a quantum-dot based “Qubyte” register

Cited by 103 publications

References 37 publications

Simulation of 1D Topological Phases in Driven Quantum Dot Arrays

Simulation of 1D Topological Phases in Driven Quantum Dot Arrays

Site-Selective Quantum Control in an Isotopically Enriched Si28/Si0.7Ge0.3 Quadruple Quantum Dot

Efficient Orthogonal Control of Tunnel Couplings in a Quantum Dot Array

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