Engineering, control and longitudinal readout of Floquet qubits

Abstract

Properties of time-periodic Hamiltonians can be exploited to increase the dephasing time of qubits and to design protected one and two-qubit gates. Recently, Huang et al. [Phys. Rev. Applied 15, 034065 (2021)] have shown that time-dependent Floquet states offer a manifold of working points with dynamical protection larger than the few usual static sweet spots. Here, we use the framework of many-mode Floquet theory to describe approaches to robustly control Floquet qubits in the presence of multiple drive tones. Following the same approach, we introduce a longitudinal readout protocol to measure the Floquet qubit without the need of first adiabatically mapping back the Floquet states to the static qubit states, which results in a significant speedup in the measurement time of the Floquet qubit. The analytical approach developed here can be applied to any Hamiltonian involving a small number of distinct drive tones, typically the study of standard parametric gates for qubits outside of the rotating-wave approximation.

Atom Interferometry with Floquet Atom Optics

“…In addition to facilitating the spectral design of dressed states, Floquet modulation can be used to engineer the time-domain dynamics of two-level systems in the presence of a strong drive [5,6]. This finds application in quantum information, where periodic driving can increase the robustness of quantum superpositions against decoherence and dephasing [7,8], as well as improve the fidelity of quantum gate operations [9,10]. Such high-fidelity state manipulations are closely related to atom optics used in lightpulse atom interferometry, where an atomic system is interrogated with light at optical frequencies to introduce inertial sensitivity [11,12].…”

Atom Interferometry with Floquet Atom Optics

“…In addition to facilitating the spectral design of dressed states, Floquet modulation can be used to engineer the time-domain dynamics of two-level systems in the presence of a strong drive [5,6]. This finds application in quantum information, where periodic driving can increase the robustness of quantum superpositions against decoherence and dephasing [7,8], as well as improve the fidelity of quantum gate operations [9,10]. Such high-fidelity state manipulations are closely related to atom optics used in light-pulse atom interferometry, where an atomic two-level system is interrogated on an optical transition to introduce inertial sensitivity [11,12].…”