Velocity-sorting and stochastic resonances in cold atom optical lattices: Path toward efficient nano-devices
Abstract
The overarching goal of this experimental proposal is to coherently control the motion of atoms with light at the forefront of nanoscale atomic transport, where Brownian fluctuations in the environment and random quantum fluctuations in the system dominate. These fluctuations can be exquisitely controlled with the aim to realize efficient nano-devices. For reasons that remain poorly understood, all artificial nano-devices manufactured to date are significantly outperformed by naturally occurring biological nano-machines, often by many orders of magnitude. These bio-molecular motors power the processes of life despite existing in exceedingly noisy environments where they are swamped by incessant Brownian collisions with surrounding water molecules. Current theoretical understanding of why bio-molecular motors are so efficient is that, counter-intuitively, they seem capable of harnessing energy from the random environmental noise by utilizing Òstochastic resonanceÓ: The efficiency of these ÒBrownian motorsÓ undergoes a maximum as the noise in the system is increased. Cold atoms confined in optical lattices offer an ideal experimental test bed for elucidating proof-of-principle nano-motors which convert random fluctuations to useful work. In the case of atoms interacting with light, the random atomic recoils owing to spontaneous emission replicate the thermal Brownian fluctuations in bio-molecular motors, and these spontaneous emission rates can be precisely controlled with laser intensity and detuning. Remarkably, the noise fueling the atomic motor need not always arise from fluctuations in the environment as in the Brownian motor - the fluctuations may be a quantum property intrinsic to the system, e.g., quantum tunneling of atoms across adjacent lattice sites. This project focuses on achieving, for the first time, stochastic resonances in optical lattices in both the classical and the quantum domains, paving the path toward high-efficiency artificial nano devices. A classical stochastic resonance refers to the case where the random fluctuations powering the nano-motor are classically coupled from the environment into the system, as in the Brownian motor. We explore the possibility of creating a Brownian ratchet capable of sorting a selected velocity-class of atoms. Further, we propose a first observation of a quantum stochastic resonance in an optical lattice where the random fluctuations powering the Òquantum motorÓ are an intrinsic quantum property of the system. This proposal has four specific objectives. First, a novel spontaneous emission-enabled Brownian ratchet capable of sorting a selected velocity class of atoms will be developed. There is great recent interest in noise-enabled ratchets for developing precise particle-sorting tools, as well as for realizing novel Maxwell demons. Second, the efficiency of this velocity-selective Brownian ratchet will be experimentally optimized, guided by theoretical simulations. Ratchet efficiency is measured by the Peclet number, which is yet to be systematically measured in cold atoms. The PI and his group will search parameter space in optical lattices to explore whether Peclet numbers comparable to bio-molecular motors can be achieved. Third, a classical stochastic resonance in optical lattices will be demonstrated by showing a peak in ratchet efficiency as the spontaneous emission rate is tuned. The phenomenon of stochastic resonance has great significance in diverse areas of science and technology, yet remains barely explored in optical lattices. Fourth, a first observation of quantum stochastic resonance in cold atoms, resulting from synchronization between a weak driving frequency and the stochastic quantum tunneling rate, will be experimentally demonstrated. A dark state-based ÒgrayÓ optical lattice will be created in which quantum tunneling events dominate, in order to observe quantum stochastic resonance.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 25, 2021
- Source ID
- W911NF2110120
Entities
People
- Samir Bali
Organizations
- Army Contracting Command
- Miami University
- United States Army