In situ magnetic-field stabilization for quantum-gas experiments

Abstract

We demonstrate a minimally-destructive in situ technique for measuring and stabilizing slowly-drifting magnetic fields in ultracold-atom experiments. While conventional magnetic-field sensors such as Hall, giant magnetoresistive, or fluxgate-based devices are broadly used, their accuracy, precision and dynamic range can be limited. In addition, these sensors are typically positioned at least several centimeters away from the in-vacuum atomic system, as their operation creates perturbing magnetic fields, and their placement is limited by geometric constraints imposed by the vacuum system. We overcome these issues by using the atomic system itself as a built-in magnetometer. To that end, we employ a pair of weak measurements to determine the Zeeman splitting -- and thereby the magnetic field -- of a magnetically sensitive atomic transition. We provide closed-form expressions quantifying the trade-offs between measurement noise, dynamic range, and atom loss. This procedure is demonstrated with ultracold Rb-87, weakly measured using partial-transfer absorption imaging. We then incorporate a Kalman filter to stabilize the magnetic field; this eliminated long-term drift in the ambient field (as high as ~70 nT/hr) in exchange for a modest increase in shot-to-shot variability from 1.8(2) nT to 2.0(2) nT.

See Ancillary files for experimental data and a reference for the feedback-locking loop

References in corpus (25)

• Many-Body Physics with Ultracold Gases
• Feshbach Resonances in Ultracold Gases
• A spin-orbit coupled Bose-Einstein condensate
• Quantum computing with atomic qubits and Rydberg interactions: Progress and challenges
• Atomic Clocks for Geodesy
• Arbitrarily accurate composite pulses
• Strong saturation absorption imaging of dense clouds of ultracold atoms
• Rapid production of ${}^{87}$Rb BECs in a combined magnetic and optical potential
• Direct observation of zitterbewegung in a Bose-Einstein condensate
• Geometrical pumping with a Bose-Einstein condensate
• Neutral Atom Quantum Computing Hardware: Performance and End-User Perspective
• Magnetic field stabilization system for atomic physics experiments
• Partial-Transfer Absorption Imaging: A versatile technique for optimal imaging of ultracold gases
• Controlling the magnetic field sensitivity of atomic clock states by microwave dressing
• A scripted control system for autonomous hardware timed experiments
• Calibrating High Intensity Absorption Imaging of Ultracold Atoms
• Synthetic clock transitions via continuous dynamical decoupling
• Design and characterisation of a compact magnetic shield for ultracold atomic gas experiments
• Composite pulses with errant phases
• Magic-wavelength Faraday probe measures spin continuously and without light shifts
• Active stabilization of kilogauss magnetic fields to the ppm level for magnetoassociation on ultranarrow Feshbach resonances
• Fourier transform spectroscopy of a spin-orbit coupled Bose gas
• Repeated Measurements with Minimally Destructive Partial-Transfer Absorption Imaging
• Progress toward a zero-magnetic-field environment for ultracold-atom experiments
• Single-shot reconstruction of the density profile of a dense atomic gas