Single-Species Atomic Comagnetometer Based on $^{87}\mathrm{Rb}$ Atoms

Single-Species Atomic Comagnetometer Based on ${}^{87}{Rb}$ Atoms

Zhiguo Wang, Xiang Peng, Rui Zhang, Hui Luo, Jiajia Li, Zhiqiang Xiong, Shanshan Wang, and Hong Guo

Phys. Rev. Lett. 124, 193002 – Published 13 May 2020

Abstract

The comagnetometer has been one of the most sensitive devices with which to test new physics related to spin-dependent interactions, but the comagnetometers based on overlapping ensembles of multiple spin species usually suffer from systematic errors due to magnetic field gradients. Here, we propose a comagnetometer based on the Zeeman transitions of the dual hyperfine levels in ground-state ${}^{87}{Rb}$ atoms, which shows nearly negligible sensitivity to variations of laser power and frequency, magnetic field, and magnetic field gradients. We measured the hypothetical spin-dependent gravitational energy of the proton with the comagnetometer, which is smaller than $4 \times 10^{- 18} eV$ , comparable to the most stringent existing constraint. Through optimizing the system parameters such as cell temperature, laser power, amplitude of driving magnetic field, as well as choosing better current source, it is possible to improve the sensitivity of the comagnetometer further.

Received 26 April 2019
Accepted 6 April 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.193002

Physics Subject Headings (PhySH)

Quantum metrology Tests of fundamental symmetries

Atomic ensemble

Optically detected magnetic resonance

Atomic, Molecular & OpticalGeneral Physics

Authors & Affiliations

Zhiguo Wang ^1,2, Xiang Peng³, Rui Zhang ⁴, Hui Luo^1,2,*, Jiajia Li¹, Zhiqiang Xiong¹, Shanshan Wang¹, and Hong Guo ^3,†

¹College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, People’s Republic of China
²Interdisciplinary Center of Quantum Information, National University of Defense Technology, Changsha 410073, People’s Republic of China
³State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, People’s Republic of China
⁴College of Liberal Arts and Sciences, National University of Defense Technology, Changsha 410073, People’s Republic of China

^*Corresponding author. luohui.luo@163.com
^†Corresponding author. hongguo@pku.edu.cn

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 124, Iss. 19 — 15 May 2020

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
Experimental setup. A spherical glass cell filled with an excess of ${}^{87}{Rb}$ is placed in the magnetic field shield. A set of solenoids are used to produce the bias magnetic field in the $z$ direction and the driving magnetic field in the $x$ direction. The probe light from a DFB laser at 780 nm propagates through a linear polarizer (polarization axis along the $y$ axis), a collimator made with two lenses, and a neutral density filter. The probe laser propagates through the cell and then is focused with a lens. A half-wave plate, a polarization beam splitter, and a balanced detector made up of two photodiodes are used to detect the paramagnetic Faraday rotation signal. The difference of the two photodiodes’ signal is digitized through an analog-to-digital converter (ADC). The output of an oscillator (OSC) is sent to a digital-to-analog converter (DAC) and then drives the $x$ coils to produce an oscillating magnetic field $B_{x}$ . We obtain the Zeeman spectrum of the Rb atoms by scanning the frequency of $B_{x}$ and recording the $R$ channel of a lock-in amplifier (LIA) made with the Labview™ program. The amplitude of $B_{x}$ is set as 0.1 nT and the frequency is changed linearly in the scan process. The $z$ coils are driven by a stable current source, producing $B_{0} \approx 11.72 μ T$ . A set of anti-Helmholtz coils are also used to produce the magnetic field gradient $\partial B_{z} / \partial z$ .
Reuse & Permissions
Figure 2
(a) Typical Zeeman spectrum of ${}^{87}{Rb}$ atoms at $11.72 μ T$ , acquired by recording $r$ ( $R$ -channel of lock-in amplifier) when scanning the frequency of $B_{x}$ . The gyromagnetic ratio of the $F = 1$ hyperfine level in ground state is $γ_{1} = 7023.69 Hz / μ T$ and that of $F = 2$ is $γ_{2} = 6995.83 Hz / μ T$ . As a result, the two Zeeman transitions can be distinguished clearly. (b) Fitting curve with Lorentzian profile for $F = 2$ magnetic resonance signal. The legends Exp. and Fit denote experimental data and fitting curves, respectively. (c) Fitting curve for $F = 1$ magnetic resonance signal. The Zeeman spectrum is a bit asymmetric, mainly because the frequency scanning is a transient process. For these data, the probe laser power is $200 μ W$ .
Reuse & Permissions
Figure 3
Measured NFR ( $ν_{2} / ν_{1} - 0.996 033924$ ) as a function of laser frequency for laser powers of $200 μ W$ and $450 μ W$ , demonstrating low sensitivity to variations of laser frequency and power. The laser frequency in the $x$ axis is shifted relative to the transition frequency from $5 {{}^{2}S}_{1 / 2} (F = 1)$ of the ${}^{87}{Rb}$ $D_{2}$ line. At some frequencies, only one of the hyperfine magnetic resonance signals was larger than noise background, so the frequency ratio could not be obtained. The laser power was measured at the entrance hole of the magnetic field shield.
Reuse & Permissions
Figure 4
Measured NFR as a function of bias magnetic field $B_{z}$ , demonstrating extremely low sensitivity to magnetic field variation. $B_{z}$ is changed by tuning the current flowing through the $z$ coils. At first, we obtained the middle 11 points, which do not show the NFR trend with magnetic field. Therefore, we measured the NFR with a slightly larger magnetic field variation; that is, the two points at the sides, which also do not show the NFR trend with magnetic field. For these data, the probe laser power is $200 μ W$ .
Reuse & Permissions
Figure 5
NFR as a function of magnetic field gradient $\partial B_{z} / \partial z$ , demonstrating low sensitivity to magnetic field gradient variation. We use anti-Helmholtz coils to produce $\partial B_{z} / \partial z$ , the magnitude of which is changed by controlling the current.
Reuse & Permissions
Figure 6
Results of spin-gravity coupling measurement over a period of 16 000 min. (a) The calculated $Δ R$ based on the measured $R_{\pm}$ . (b) Histograms of $Δ R$ with Gaussian fitting: solid lines in the histograms are Gaussian-fitting curves, indicating $Δ R$ is subject to normal distribution. (c) Allan variance analysis for $Δ R$ , showing a slight drift at the 100-h timescale. The measured $Δ R$ scatters somewhat larger after 5000 points mainly due to fluctuations of the gas flowing from an air-conditioner in the laboratory, which blows on the experimental setup.
Reuse & Permissions

Physical Review Letters

Single-Species Atomic Comagnetometer Based on Rb87 Atoms

Zhiguo Wang, Xiang Peng, Rui Zhang, Hui Luo, Jiajia Li, Zhiqiang Xiong, Shanshan Wang, and Hong Guo

Phys. Rev. Lett. 124, 193002 – Published 13 May 2020

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

Article Text (Subscription Required)

Supplemental Material (Subscription Required)

References (Subscription Required)

Issue

Access Options

Authorization Required

Other Options

Download & Share

Images

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Log In

Search

Article Lookup

Paste a citation or DOI

Enter a citation

Single-Species Atomic Comagnetometer Based on ${}^{87}{Rb}$ Atoms