Electrically tunable quantum interference of atomic spins on surfaces

TL;DR

This paper demonstrates electrical control of quantum interference in atomic spins on surfaces, enabling all-electrical quantum manipulation crucial for spin-based quantum computing.

Contribution

It introduces a method to electrically tune quantum interference in atomic spins using bias voltages in a scanning tunneling microscope, achieving Landau-Zener-Stückelberg-Majorana interferometry.

Findings

Electrical modulation of spin interactions via bias voltage.

Observation of multiphoton resonances in LZSM interference.

Distinct interference patterns for coupled spins with tunable interactions.

Abstract

Controlling quantum interference near avoided energy-level crossings is crucial for fast and reliable coherent manipulation in quantum information processing. However, achieving tunable quantum interference in atomically-precise engineered structures remains challenging. Here, we demonstrate electrical control of quantum interference using atomic spins on an insulating film in a scanning tunneling microscope. Using bias voltages applied across the tunnel junction, we modulate the atomically-confined magnetic interaction between the probe tip and surface atoms with a strong electric field, and drive the spin state rapidly through the energy-level anticrossing. This all-electrical manipulation allows us to achieve Landau-Zener-St\"uckelberg-Majorana (LZSM) interferometry on both single spins and pairs of interacting spins. The LZSM pattern exhibits multiphoton resonances, and its asymmetry suggests that the spin dynamics is influenced by spin-transfer torque of tunneling electrons. Multi-level LZSM spectra measured on coupled spins with tunable interactions show distinct interference patterns depending on their many-body energy landscapes. These results open new avenues for all-electrical quantum manipulation in spin-based quantum processors in the strongly driven regime.