Abstract
The concept of `Floquet engineering' relies on an external periodic drive to realise novel, effectively static Hamiltonians. This technique is being explored in experimental platforms across physics, including ultracold atoms, laser-driven electron systems, nuclear magnetic resonance, and trapped ions. The key challenge in Floquet engineering is to avoid the uncontrolled absorption of photons from the drive, especially in interacting systems in which the excitation spectrum becomes effectively dense. The resulting dissipative coupling to higher-lying modes, such as the excited bands of an optical lattice, has been explored in recent experimental and theoretical works, but the demonstration of a broadly applicable method to mitigate this effect is lacking. Here, we show how two-path quantum interference, applied to strongly-correlated fermions in a driven optical lattice, suppresses dissipative coupling to higher bands and increases the lifetime of double occupancies and spin-correlations by two to three orders of magnitude. Interference is achieved by introducing a weak second modulation at twice the fundamental driving frequency with a definite relative phase. This technique is shown to suppress dissipation in both weakly and strongly interacting regimes of a driven Hubbard system, opening an avenue to realising low-temperature phases of matter in interacting Floquet systems.
Highlights
Dissipation emerges when a system is coupled to a large number of degrees of freedom in its environment
Dissipation naturally arises when the low-energy modes are coupled to lossy excited modes by the drive. This form of dissipation presents a formidable challenge to Floquet engineering, in which periodic driving is used to create a host of novel, effectively static Hamiltonians, with ultracold atoms [1,2,3,4] and beyond [5,6,7,8,9]
Numerical calculations on a two-site, two-band Hubbard model reveal excellent performance of two-frequency canceling even when driving on resonance with another energy scale, e.g., the Hubbard U
Summary
Dissipation emerges when a system is coupled to a large number of degrees of freedom in its environment. Dissipation naturally arises when the low-energy modes are coupled to lossy excited modes by the drive. This form of dissipation presents a formidable challenge to Floquet engineering, in which periodic driving is used to create a host of novel, effectively static Hamiltonians, with ultracold atoms [1,2,3,4] and beyond [5,6,7,8,9]. We demonstrate control of dissipation by introducing a second excitation pathway at twice the fundamental driving frequency and tuning the relative phase [27,28,29,30] between the two drives to maximize quantum interference The performance of this method of dissipation control is quantified by comparing the driven lattice to an equivalent static configuration. The first relevant resonance is a two-photon process at frequency ω (shown in orange), whereas the single-photon transition is located at 2ω (blue). (c) When applying two driving frequencies simultaneously with matched transition strengths, tuning the relative phase φ coherently enhances or suppresses dissipative coupling to higher bands
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