Coherent tunneling adiabatic passage with the alternating coupling scheme

Abstract

The use of adiabatic passage techniques to mediate particle transport through real space, rather than phase space, is becoming an interesting possibility. We have investigated the properties of coherent tunneling adiabatic passage (CTAP) with alternating tunneling matrix elements. This coupling scheme, not previously considered in the donor in silicon paradigm, provides an interesting route to long-range quantum transport. We introduce simplified coupling protocols and transient eigenspectra as well as a realistic gate design for this transport protocol. Using a pairwise treatment of the tunnel couplings for a five-donor device with 30 nm donor spacings, 120 nm total chain length, we estimate the timescale required for adiabatic operation to be approximately 70 ns, a time well within the measured electron spin and estimated charge relaxation times for phosphorus donors in silicon.

Spatial adiabatic passage: a review of recent progress

“…Adiabaticity arguments show that the time for transport across a chain of n sites scales with √ n to leading order [104]. Extending electronic transport via the straddling scheme has also been discussed [85,105]. Another major reason for exploring SAP for chargebased transport in phosphorus-in-silicon quantum architectures is related to the timescales for control and tunnelling.…”

“…The relative robustness from decoherence arises from the suppression of population in the bus states, and is strongest in the case of the straddling scheme. For a multi-state chain with 2n + 1 sites, labelled in increasing order from left (|1 ) to right (|2n + 1 ), the general solution for the dark state is [85,105]…”

Spin-selective electron transfer in a quantum dot array

“…Stimulated Raman adiabatic passage (STIRAP) has been widely studied for population transfer of molecules [39][40][41][42][43][44][45][46], transport of single atoms [47][48][49][50][51][52], electrons [53,54], and BECs [55][56][57][58]. The remarkable properties of this protocol have already been demonstrated in diverse areas such as chemical reaction dynamics [59], laser-induced cooling of atomic gases [60], light beams propagating in three evanescently coupled optical waveguides [61][62][63][64], sound propagation in sonic crystals [65], and control of a superconducting qubit [66].…”

Coherent tunneling via adiabatic passage in a three-well Bose-Hubbard system

“…of this system maps onto CTAP of a single particle along a chain of 2N + 1 sites via an alternating coupling protocol [41][42][43]. This mapping allows us to apply several analytical results to the problem, which would otherwise be computationally intensive, since the size of the Hilbert space basis is of order N 2 .…”