Wavefunction Engineering for Atom Interferometers using Yb BECs

Atom interferometry is a well-established technique for leveraging the wave-like nature of neutral atoms for precise metrology, with a plethora of applications in fundamental physics, precision measurement, and inertial sensing [1,2]. Two distinct paradigms exist for operating an atom interferometer: the more traditional free-fall geometries and the more recent trapped interferometers. In either paradigm, increasing the sensitivity of the interferometer requires coherent control of the wavefunctions of the two arms in a phase-stable manner to both increase the spacetime area enclosed and protect against sources of noise or decoherence. In the context of an optical lattice used to either trap the atoms or impart many photon momenta in large momentum transfer (LMT) schemes, the phenomenon of Bloch oscillations (BOs) arises. The phase imprinted on the atomic wavefunction from BOs are crucial to determine and control for up-scaling atom interferometric sensors [3]. Here, we present the application of a coherent control technique developed in past work [4], dubbed the “magic depth” of excited states in an optical lattice, to both trapped and pulsed interferometer schemes. In analogy to the magic wavelength for an optical lattice clock where the AC light shift of the confining potential is equal for both internal states and is thus insensitive to fluctuations, the magic depth of an optical lattice is the point where the differential phase imprinted on two external states from lattice intensity fluctuations is insensitive to first order. Using BECs of 174Yb, we investigate the performance of lattice-trapped atom interferometers in both the ground and first excited band at the magic depth, for different wavepacket separations and lattice hold times. We also present progress towards a BO-enhanced LMT pulsed interferometer with momentum separations approaching the kilo-recoil (1000 photon momentum) regime.

[1] Morel et al., 2020. Nature 588, 61-65.

[2] Asenbaum et al., 2020. PRL 125, 191101

[3] Rahman et al., 2024. PRR 6, L022012.

[4] McAlpine et al., 2020. PRA 101, 023614.