An Adaptable Route to Fast Coherent State Transport via Bang-Bang-Bang Protocols

Abstract: Fast coherent state transport is essential to quantum computation and quantum information processing. While an adiabatic transport of atomic qubits guarantees a high fidelity of the state preparation, it requires a long timescale that defies efficient quantum operations. Here, we propose an adaptable and fast bang-bang-bang (BBB) protocol, utilizing a combination of forwardand backward-moving trap potentials, to expedite the coherent state transport. This protocol approaches the quantum speed limit under a harmonic trap potential, surpassing the performance by the forward-moving-only potential protocols. We further showcase the advantage of applying squeezed coherent state evolution under a deeper potential followed by a weaker one, where a design of symmetric squeezing potential transports promotes an even shorter timescale for genuine state preparation. Our protocols outperform conventional forward-moving-only methods, providing new insights and opportunities for rapid state transport and preparation, ultimately advancing the capabilities of quantum control and quantum operations.