Electron States in Parallel Double Quantum Dots with a Tunable Inter-Dot Coupling

Abstract

We study the electron states on lateral double quantum dots coupled in parallel. The charge stability diagrams are given in terms of the gate voltages of both dots. We discover that the two electron states translate from separated states to coupled states continuously by increasing the inter-dot coupling strength. Our results demonstrate that the parallel-quantum-dot tunability bodes well for future quantum computing applications.

Characterization of Qubit Dephasing by Landau-Zener-Stückelberg-Majorana Interferometry

“…Our steady-state method is remarkably simple compared to the alternative pulsed gate experiments. Our two-electron charge qubit is affected by slow charge noise limiting T 2 = /λ to 0.2 ns but a coherence time of T 2 0.2 µs being much longer than previously reported values in quantum dot charge qubits [13,32,33]. The clock-speed of our qubit, ∆/h 3.1 GHz, which limits T 2 at T 20 mK and¯ = 0, would then provide enough time for > 600 quantum operations.…”

“…The probability to remain in the initial qubit state, P LZ = exp(−π∆ 2 /2 v), thereby grows with the velocity v = d /dt, here assumed to be constant [1][2][3][4]. Because the relative phase between the split wavepackets depends on their energy evolutions, repeated passages by a periodic modulation (t) =¯ +A cos(Ωt), give rise to so-called LZSM quantum interference [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. We present a breakthrough which * These authors contributed equally to this work.…”

Quantum wire and magnetic control of a spin qubit in the Landau–Zener–Stückelberg interferometry transition

“…LZS interference has been studied in several experiments in a multi-anticrossing level structure [12][13][14][15][16]. In these experimental realizations, the periodic modulation between the two extrema of the transition energy has been achieved by driving the qubit longitudinally with a triangular or sinusoidal signal.…”