## Floquet-engineering Counterdiabatic Protocols in Quantum Many-body Systems

**Speaker:**Mohit Pandey

**When:**June 12, 2019 (Wed), 01:30PM to 02:30PM (add to my calendar)

**Location:**SCI 328

*This event is part of the Preliminary Oral Exam. *

Examining Committee: David Campbell, Anatoli Polkovnikov, Alexander Sushkov, A. Liam Fitzpatrick

Abstract:

Noise and decoherence caused by the environment are two major challenges in applying adiabatic protocols to quantum technologies. Counter-diabatic (CD) driving protocols, which are also known as "shortcuts-to-adiabaticity", provide powerful alternatives for controlling a quantum system. While CD driving is theoretically known, obtaining and implementing it in many-body systems is a formidable task, requiring knowledge of the spectral properties of the instantaneous Hamiltonians and control of highly nonlocal multibody interactions. We show how an approximate gauge potential can be systematically built up as a series of nested commutators, remaining well-defined in the thermodynamic limit. Furthermore, the resulting CD driving protocols can be realized up to arbitrary order without leaving the available control space using tools from Floquet engineering. We apply this approach to a qubit and experimentally demonstrate its robust performance with the electronic spin of a Nitrogen-vacancy center in diamond [1]. Moreover, we also apply this to few- and many-body quantum systems, where the resulting Floquet protocols significantly suppress dissipation and provide a drastic increase in fidelity [2].

[1] *Boyers, E., *Pandey, M., Campbell, D. K., Polkovnikov, A., Sels, D., & Sushkov, A. O. (2018). Floquet-engineered quantum state manipulation in a noisy qubit. arXiv preprint arXiv:1811.09762.

[2] Claeys, P. W., Pandey, M., Sels, D., & Polkovnikov, A. (2019). Floquet-engineering counterdiabatic protocols in quantum many-body systems. arXiv preprint arXiv:1904.03209