New Experimental Limits on Exotic Spin-Spin-Velocity-Dependent Interactions by Using SmCo5 Spin Sources

Abstract

We report the latest results of searching for possible new macro-scale spin-spin-velocity-dependent forces (SSVDFs) based on specially designed iron-shielded SmCo5 (ISSC) spin sources and a spin exchange relaxation free (SERF) co-magnetometer. The ISSCs have high net electron spin densities of about 1.7 × 10 21 cm −3 , which mean high detecting sensitivity; and low magnetic field leakage of about ∼mG level due to iron shielding, which means low detecting noise. With help from the ISSCs, the high sensitivity SERF co-magnetometer, and the similarity analysis method, new constraints on SSVDFs with forms of V6+7, V8, V15, and V16 have been obtained, which represent the tightest limits in force range of 5 cm -1 km to the best of our knowledge.

Interference in Atomic Magnetometry

“…[11][12][13] Atomic magnetometers have been demonstrated with subfemtotesla sensitivity [14][15][16] and quickly become the promising modality for precision magnetic measurements. [17][18][19] Particularly, atomic magnetometers are applied to nuclear magnetic resonance (NMR) in ultralow magnetic field, and deliver new promising applications ranging from chemical analysis, [20][21][22][23] quantum control [24][25][26][27] to fundamental physics. [28][29][30][31] Although great progress has been achieved for the development of atomic magnetometers, further improvement of their performance requires a full understanding of the relevant detection processes.…”

“…[ 11–13 ] Atomic magnetometers have been demonstrated with subfemtotesla sensitivity [ 14–16 ] and quickly become the promising modality for precision magnetic measurements. [ 17–19 ] Particularly, atomic magnetometers are applied to nuclear magnetic resonance (NMR) in ultralow magnetic field, and deliver new promising applications ranging from chemical analysis, [ 20–23 ] quantum control [ 24–27 ] to fundamental physics. [ 28–31 ]…”

Search for exotic spin-dependent interactions with a spin-based amplifier

“…The field slightly tilts 129 Xe spins and induces an oscillating 129 Xe transverse magnetization that is read out by 87 Rb spins. The spin dynamics can be described by the coupled Bloch equations ( 19 , 40 , 46 ) where P e ( P n ) is the polarization of 87 Rb electron ( 129 Xe nucleus), γ e (γ n ) is the gyromagnetic radio of the 87 Rb electron ( 129 Xe nucleus), Q is the electron slowing-down factor that originated from hyperfine interaction and spin-exchange collisions, is the applied bias field; ( ) is the maximum magnetization of 87 Rb electron ( 129 Xe nucleus) associated with full spin polarizations, ( ) is the equilibrium polarization of the 87 Rb electron ( 129 Xe nucleus), T e is the common relaxation time of 87 Rb electron spins, and T 1 n ( T 2 n ) is the longitudinal (transverse) relaxation time of 129 Xe spins. The Fermi-contact interaction between 87 Rb and 129 Xe pairs introduces an effective magnetic field , where β = 8πκ 0 /3 ( 40 , 46 , 47 ).…”

“…Some of them may break the charge, parity, and time-reversal symmetries or their combinations ( 11 , 37 ); they were introduced to understand the symmetries of charge conjugation and parity in quantum chromodynamics ( 3 ). Many experiments have been performed to search for static spin-dependent interactions ( 12 , 14 – 16 , 20 – 23 , 25 , 26 , 29 , 31 , 32 ), while the velocity-dependent interactions have been studied less extensively ( 18 , 19 , 24 , 28 , 30 ). Following the notation in ( 37 , 38 ), the spin- and velocity-dependent interactions to be studied here are where f 4+5 and f 12+13 are dimensionless coupling constant, c is the speed of light in vacuum, is the spin vector and m is the mass of the polarized fermion, v is the relative velocity between two interacting fermions, is the unit vector in the direction between them, and λ = ħ( m b c ) −1 is the force range (or the boson Compton wavelength) with m b being the light boson mass.…”

Constraints on the Velocity and Spin Dependent Exotic Interaction at the Micrometer Range

“…For the spin-dependent interactions, the effect of one particle acting on another can be treated as an exotic magnetic field acting on the other particle's spin. Using the spin as a sensor, one can detect the new interactions by measuring the spin response to the exotic magnetic field, such as in experiments with magnetometers [16][17][18][19][20], trapped ions [21,22], nitrogen vacancy color center in diamond [23,24], and neutron or polarized 3 He atoms [25][26][27]. A superconducting quantum interference device was also used to probe the magnetization of paramagnetic material induced by the exotic magnetic field [28][29][30].…”