Coherent transfer of singlet-triplet qubit states in an architecture of triple quantum dots

Feng, MengKe; Kwong, Chang Jian; Koh, Teck Seng; Kwek, Leong Chuan

doi:10.1103/physrevb.97.245428

Cited by 9 publications

(5 citation statements)

References 52 publications

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“…In addition Ref. [23] applies an electrical control over the detuning energy of the quantum states of the two-electron singlet-triplet qubit across a chain of three quantum dots.…”

Section: Introductionmentioning

confidence: 99%

High-fidelity quantum control via Autler-Townes splitting

Delvecchio

Kirova²,

Arimondo³

et al. 2022

Phys. Rev. A

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We propose quantum control protocols for the high-fidelity preparation of target-states in systems with Autler-Townes splitting. We investigate an approximated three-level system obtained from a four-level one by adiabatically eliminating a state that does not participate in the evolution. In our work we use linear, arctan and Roland-Cerf functions for transferring population between two eigenstates of the system obtaining a high fidelity for long evolution times. Additionally, in order to overcome the restriction given by the lifetimes of the experimental setup, we propose an accelerated adiabatic evolution with a shortcut to adiabaticity protocol, which allows us to reach fidelities close to one but much faster.

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“…In addition Ref. [23] applies an electrical control over the detuning energy of the quantum states of the two-electron singlet-triplet qubit across a chain of three quantum dots.…”

Section: Introductionmentioning

confidence: 99%

High-fidelity quantum control via Autler-Townes splitting

Delvecchio

Kirova²,

Arimondo³

et al. 2022

Phys. Rev. A

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“…Two-qubit entangling gates can be based on exchange [14] or capacitive [18][19][20][21] coupling. The exchange interaction is fast but short-ranged, giving rise to hybrid approaches like spinshuttling [22][23][24][25][26] and circuit QED [27,28]. Because the exchange interaction arises from spin-conserving tunneling, two-qubit gates based on exchange have the potential for leakage.…”

Section: Introductionmentioning

confidence: 99%

Two-qubit sweet spots for capacitively coupled exchange-only spin qubits

Feng,

Zaw,

Koh

2021

Preprint

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The implementation of high fidelity two-qubit gates is a bottleneck in the progress towards universal quantum computation in semiconductor quantum dot qubits. We study capacitive coupling between two triple quantum dot spin qubits encoded in the S = 1/2, Sz = −1/2 decoherence-free subspace -the exchange-only (EO) spin qubits. We report exact gate sequences for CPHASE and CNOT gates, and demonstrate theoretically, the existence of multiple two-qubit sweet spots (2QSS) in the parameter space of capacitively coupled EO qubits. Gate operations have the advantage of being all-electrical, but charge noise that couple to electrical parameters of the qubits cause decoherence. Assuming noise with a 1/f spectrum, two-qubit gate fidelities and times are calculated, which provide useful information on the noise threshold necessary for fault-tolerance. We study two-qubit gates at single and multiple parameter 2QSS. In particular, for two existing EO implementations -the resonant exchange (RX) and the always-on exchange-only (AEON) qubits -we compare two-qubit gate fidelities and times at positions in parameter space where the 2QSS are simultaneously single-qubit sweet spots for the RX and AEON. These results provide a potential route to the realization of high fidelity quantum computation.

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“…A different flavor of mobile qubits are spins which are shuttled in a bucket-brigade manner between neighboring empty quantum dots [24]. This method to turn stationary into moving qubits has received much attention recently [25][26][27][28][29][30][31][32]. Coherent spin transfer has already been demonstrated in GaAs devices [33,34], while charge shuttling down an array of 9 series-coupled QDs has been demonstrated in silicon [35] and applications beyond transport are conceivable [36,37].…”

Section: Introductionmentioning

confidence: 99%

Spin shuttling in a silicon double quantum dot

Ginzel,

Mills,

Petta

et al. 2020

Preprint

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The transport of quantum information between different nodes of a quantum device is among the challenging functionalities of a quantum processor. In the context of spin qubits, this requirement can be met by coherent electron spin shuttling between semiconductor quantum dots. Here we theoretically study a minimal version of spin shuttling between two quantum dots. To this end, we analyze the dynamics of an electron during a detuning sweep in a silicon double quantum dot (DQD) occupied by one electron. Possibilities and limitations of spin transport are investigated. Spin-orbit interaction and the Zeeman effect in an inhomogeneous magnetic field play an important role for spin shuttling and are included in our model. Interactions that couple the position, spin and valley degrees of freedom open a number of avoided crossings in the spectrum allowing for diabatic transitions and interfering paths. The outcomes of single and repeated spin shuttling protocols are explored by means of numerical simulations and an approximate analytical model based on the solution of the Landau-Zener problem. We find that a spin infidelity as low as 1 − Fs 0.002 with a relatively fast level velocity of α = 600 µeV ns −1 is feasible for optimal choices of parameters or by making use of constructive interference.

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Coherent transfer of singlet-triplet qubit states in an architecture of triple quantum dots

Cited by 9 publications

References 52 publications

High-fidelity quantum control via Autler-Townes splitting

High-fidelity quantum control via Autler-Townes splitting

Two-qubit sweet spots for capacitively coupled exchange-only spin qubits

Spin shuttling in a silicon double quantum dot

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