A battery-powered floating current source of 100 A for precise and fast control of magnetic field

Abstract

In various leading-edge ultracold atom experiments in fields such as quantum simulation, quantum computing, and quantum precision measurement, precise and fast control of the magnetic field is important and a current source with a low noise level and high control bandwidth is required. Conventional commercial current sources, even the expensive ones, may not meet the requirements. Here, we present a battery-powered current source (BPCS) solution that has a maximum output of 100 A with a root-mean-square noise of about only 0.35 mA (integrated from 1 Hz to 3 MHz) and a control bandwidth of about 10 kHz. The large output current is sourced from a lead-acid battery, a fluxgate current sensor is used to detect the output current, and fast feedback regulation is done by using an insulated-gate bipolar transistor under the control of an analog proportional-integral controller. The battery power method eliminates the switching noise. A prepulse method is applied to shorten the settling time when the current steps down from a high level to a low level that is close to zero. These features make the BPCS a suitable analog-controlled floating current source for cold-atom experiments such as the preparation of a single 2D quantum gas and optical lattice atomic clocks.

Spin current in a spinor Bose–Einstein condensate induced by a gradient magnetic field

“…[6,18] In the cold atom systems, a magnetic field is hardly stabilized and eliminated. [19,20] The force on the spin components produced by the magnetic field gradient will induce the spin current. [16] The relating properties need to be further researched.…”

Bidirectional, Analog Current Source Benchmarked with Gray Molasses-Assisted Stray Magnetic Field Compensation

“…For this purpose, many low-noise current source designs have been developed. In many applications, such as forming a magnetic trap [5] or controlling interactions with Feshbach resonances [6], a unipolar current source is sufficient [7][8][9][10]. However, for the full control of cold samples, the ability to create a uniform magnetic field of user-defined amplitude and direction is required.…”