Atom Computing (United States)

Abstract We study spin-dynamics and quantum magnetism with ultracold highly-magnetic atoms. In particular, we focus on the interactions among rare-earth atoms localized in a site of an optical-lattice potential, modeled as a cylindrically symmetric harmonic oscillator in the presence of a weak external magnetic field. The interactions between the atoms are modeled using multi-channel Hamiltonian containing multiple spin-spin and anisotropic spin-orbit interactions with strengths that depend on the separation between the atoms. We studied the eigenenergies of the atom pair in a site for different lattice-site geometries and magnetic field strengths. In parallel, we compared these energies to those found from a simplified approach, where the complex-collisional physics is replaced by a two-length-scale pseudo-potential containing a contact and the magnetic dipole-dipole interaction. The eigenenergies within this model can be computed analytically within the Born approximation as well as non-perturbatively for stronger contact interactions. We have shown that the pseudo-potential model can accurately represent the multi-channel Hamiltonian in certain parameter regimes of the shape or geometry of the site of an optical lattice. The pseudo-potential forms the starting point for many-body, condensed matter simulations involving many atom pairs in different sites of an optical lattice.

Ultracold neutral atoms have emerged as a leading platform for scalable quantum simulation, but can they be similarly used for gate-based quantum computation? In this talk, I will present an overview of major accomplishments in academia that have spurred multiple different startups to enter the quantum computing race, focusing on the use of neutral atoms as a scalable qubit platform. With these proof of principle demonstrations in mind, I will describe Atom Computing's first prototype system and recently announced use of a unique qubit to achieve bare coherence times in excess of 20 seconds. Utilizing qubit states that are broadly insensitive to the environment they are trapped in, this system is quickly becoming a testbed for how to build programmatic control into neutral atom systems that rivals other leading quantum computing platforms.

Abstract This chapter is adapted from Physical Review Letters Volume 127, Issue 6, Page 060404, by Cheng-An Chen, Sergei Khlebnikov, and Chen-Lung Hung, published on 6 August 2021. In this chapter, we report observation of quasiparticle pair-production by a modulational instability in an atomic superfluid and present a measurement technique that enables direct characterization of quasiparticle quantum entanglement. By quenching the atomic interaction to attractive and then back to weakly repulsive, we produce correlated quasiparticles and monitor their evolution in a superfluid through evaluating the in situ density noise power spectrum, which essentially measures a “homodyne” interference between ground state atoms and quasiparticles of opposite momenta. We observe large amplitude growth in the power spectrum and subsequent coherent oscillations in a wide spatial frequency band within our resolution limit, demonstrating coherent quasiparticle generation and evolution. The spectrum is observed to oscillate below a quantum limit set by the Peres–Horodecki separability criterion of continuous-variable states, thereby confirming quantum entanglement between interaction quench-induced quasiparticles.KeywordsQuasiparticlePair productionQuantum entanglementQuench dynamicsHomodyne detectionPeres-Horodecki separabilityContinuous variableDensity power spectrum

We present a fully operational ultra-stable-laser system for cooling, trapping and manipulating Rydberg states in optical tweezer arrays of neutral Sr-atoms. Some CW-lasers are phase-coherently disciplined by an ultra-low-noise comb referenced to a sub-Hz ultra-stable-laser.