Manipulation of mobile spin coherence using magnetic-field-free electron spin resonance

Electron spin resonance (ESR) has applications in the manipulation of individual electron spins for quantum information processing(1-6). In general, ESR requires two external magnetic fields: a static field (B-0) to split the spin states in energy and an oscillating field (B-1) with the frequency resonant to the splitting energy. However, spin manipulation methods relying on real magnetic fields-much broader than the size of individual electrons-are energetically inefficient and unsuitable for future device applications. Here we demonstrate an alternative approach where the spin-orbit interaction(7) of trajectory-controlled electrons induces effective B-0 and B-1 fields. These fields are created when electron spins surf on sound waves(8-10) along winding semiconductor channels. The resultant spin dynamics-mobile spin resonance-is equivalent to the usual ESR but requires neither static nor time-dependent real magnetic fields to manipulate electron spin coherence.