Spin-selective electron transfer in a quantum dot array

Abstract

We propose a spin-selective coherent electron transfer in a silicon quantum dot array. Oscillating magnetic fields and temporally controlled gate voltages are utilized to separate the electron wave function into different quantum dots depending on the spin state. We introduce a nonadiabatic protocol based on π pulses and an adiabatic protocol which offer fast electron transfer and robustness against the error in the control-field pulse area, respectively. We also study a shortcut-to-adiabaticity protocol which compromises these two protocols. We show that this scheme can be extended to multielectron systems straightforwardly and used for nonlocal manipulations of electrons.

The experimental realization of high-fidelity ‘shortcut-to-adiabaticity’ quantum gates in a superconducting Xmon qubit

“…The detailed driving pulse is different but preserves the utilization of the phase accumulation in the fast 'adiabatic' evolution. The STA gate operations are also discussed in recent theoretical proposals [26,27]. With the improvement from a superconducting phase to Xmon qubit, the high-fidelity STA quantum gate is successfully achieved, as demonstrated by our quantum process tomography (QPT) and interleaved randomized benchmarking measurements.…”

Theoretical Study on Spin-Selective Coherent Electron Transfer in a Quantum Dot Array

“…A conducting lead (blue line) carries the AC current, I p , which produces the pump magnetic field B p = (B p , 0, 0) along the x-axis perpendicular to the two-dimensional electron gas. The conducting lead is separated from the center of Dot 0 by distance r 0 , and is tilted with respect to the z-axis by angle θ 0 to introduce the spatial inhomogeneity of B p in Dot 0 [12], which is essential for our proposal, as shown in Equation (4). We assume that the initial condition of the electron trapped in Dot 0 is a superposition of the spin-up ground state and the spin-down ground state.…”

“…It is known that all single-qubit gates, and one of two-qubit gates that entangles two qubits, such as the CNOT gate, form the universal set of gates. Entenglement can be introduced only by a non-local operation, such as the one introduced in [12]. Several types of quantum gate operations, including two-qubit quantum gates, have been demonstrated [13][14][15] by employing the exchange interaction between single spins in isotopically enriched silicon [16].…”

“…Inspired by a theoretical analysis of two-qubit gate implementation employing state-dependent potentials in cold atom systems in optical fiber array [27][28][29], we recently proposed a spin-selective electron transfer method described in [12], which realizes non-local qubit operations in a quantum dot array. This proposal also offers quantum non-demolition measurement of electron spin [30][31][32] provided that the electron position is measured without introducing the dissipation to the electron.…”

Fast-forward scaling theory for phase imprinting on a BEC: creation of a wave packet with uniform momentum density and loading to Bloch states without disturbance

“…Various schemes of STA have been proposed, e.g., the counter-diabatic [18], fast-forward [3] and invariant-based engineering protocols [19]. Applications of STA protocols have been proposed and implemented for manipulations of, e.g., atoms and molecules [10,18,[20][21][22][23][24][25], BECs [3-5, 8, 19, 26, 27], spin systems [28][29][30][31][32][33][34] including electron spin of a single nitrogen-vacancy center in diamond [35,36], various STIRAP systems [11,18,20,37,38] and also for creation of entangled states [39,40] and nonlocal two-qubit gate operations in a quantum dot array [41]. Transition probability generating function was studied from a point of view of STA [42].…”