Acoustic Traps and Lattices for Electrons in Semiconductors

Abstract

We propose and analyze a solid-state platform based on surface acoustic waves for trapping, cooling, and controlling (charged) particles, as well as the simulation of quantum many-body systems. We develop a general theoretical framework demonstrating the emergence of effective time-independent acoustic trapping potentials for particles in two- or one-dimensional structures. As our main example, we discuss in detail the generation and applications of a stationary, but movable, acoustic pseudolattice with lattice parameters that are reconfigurable in situ. We identify the relevant figures of merit, discuss potential experimental platforms for a faithful implementation of such an acoustic lattice, and provide estimates for typical system parameters. With a projected lattice spacing on the scale of ∼100nm , this approach allows for relatively large energy scales in the realization of fermionic Hubbard models, with the ultimate prospect of entering the low-temperature, strong interaction regime. Experimental imperfections as well as readout schemes are discussed.

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Plain Language Summary

The ability to trap and control atoms and molecules with electromagnetic fields has led to revolutionary advances in diverse fields such as biology, condensed-matter physics, and quantum information. These advances range from optical tweezers for probing the mechanical properties of DNA to the experimental realization of Bose-Einstein condensates, an exotic state of matter that arises when certain substances are cooled to near absolute zero. Meanwhile, improvements in the fabrication of semiconductor nanostructures have led to a proliferation of quasiparticles, an emergent behavior that arises from complex interactions among electrons and atoms. Researchers would like to trap quasiparticles to gain deeper insights into their properties and interactions. Semiconductor nanostructures known as quantum dots are excellent traps, but scaling them to encompass many particles is challenging. We propose a novel method for trapping and manipulating quasiparticles in solid-state matter.

Our proposal makes use of surface acoustic waves (SAW)—sound waves that traverse the surface of a material—thereby bringing the flexibility of electromagnetic traps to the solid-state setting and creating a new toolbox applicable to a broad class of systems. Our acoustic trapping mechanism is closely related to techniques used to trap ions, thus interconnecting two previously unrelated research fields. The SAW configuration shares the flexibility of optical lattices for atoms and may serve similarly as a basis to study many-body physics, albeit in unprecedented parameter regimes because of ultrahigh charge-to-mass ratios and long-ranged Coulomb interactions.

This technique enables a new approach to the realization of quantum simulators and synthetic quantum matter.