Speaker: Dr. Ruoyu Yin (Bar Ilan University)

Date: July 4th, 14:30- 

Style: Zoom

Title: Quantum first-hitting times with restart

Abstract:  

In our study, we explore quantum restarts for both infinite and finite systems. We begin with quantum hitting times using a monitored quantum walk on an infinite lattice, where restarts mitigate dark states and maintain ballistic propagation crucial for fast quantum search. This approach not only expedites the search but reveals unique characteristics, such as multiple minima in mean hitting times and restart-induced instabilities, distinguishing it from classical analogues. Importantly, the instability shows resilience to noise, suggesting practical observability in current quantum computing setups. For finite systems, where quantization occurs for the average recurrence time, we introduce a time-energy uncertainty relation that accounts for new effects induced by restarts. This relation links the broadening of mean hitting times near resonances to the system's intrinsic energies and recurrence time fluctuations. These findings, validated through experiments on an IBM quantum computer, highlight the utility of restart mechanisms in practical quantum experiments and enhance our understanding of quantum system dynamics under periodic strong measurements.