Floquet maser

Abstract

The invention of the maser stimulated revolutionary technologies such as lasers and atomic clocks. Yet, realizations of masers are still limited; in particular, the physics of masers remains unexplored in periodically driven (Floquet) systems, which are generally defined by time-periodic Hamiltonians and enable observation of many exotic phenomena such as time crystals. Here, we investigate the Floquet system of periodically driven 129Xe gas under damping feedback and unexpectedly observe a multimode maser that oscillates at frequencies of transitions between Floquet states. Our findings extend maser techniques to Floquet systems and open avenues to probe Floquet phenomena unaffected by decoherence, enabling a previously unexplored class of maser sensors. As a first application, our maser offers the capability of measuring low-frequency (1 to 100 mHz) magnetic fields with subpicotesla-level sensitivity, which is substantially better than state-of-the-art magnetometers and can be applied to, for example, ultralight dark matter searches.

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 ).…”

New constraints on axion-like dark matter using a Floquet quantum detector

“…These methods have been widely applied in various disciplines in condensed matter and atomic physics, enabling control over the topology and band structure of materials (34,35), the formation of time crystals (36), and modification of the effective gyromagnetic ratio of atoms and their response to external fields (37,38). Utilization of Floquet fields have long enabled to enhance the sensitivity of NMR sensors at high frequencies (39), and recently, it was proposed as an eminent avenue to enhance the performance of DM field detectors (40). However, constraints on the coupling of DM (and in particular ALPs) to fermions using Floquet techniques have never been realized until this work.…”

Limits on axions and axionlike particles within the axion window using a spin-based amplifier

“…Since the first experimental searches for exotic spin-spin interactions [2], recent progress on exploring such interactions over a broad range of particle masses has been enabled by advances in techniques including magnetometry [8,[21][22][23][24], nuclear magnetic resonance [10,20,25,26], torsionpendulum measurements [27,28], trapped ions measurements [29], nitrogen-vacancy centers in diamond [30], geoelectrons [31,32], neutron beams [9], masers [33,34] and cantilevers [35]. The tree-level interactions arising from pseudoscalar boson exchange are spin-dependent [36].…”

“…Spin sensor. To search for these pseudomagnetic fields, we use a spin-based amplifier [10,26,39,43], which employs spatially overlapping ensembles of spin-polarized 87 Rb and 129 Xe [34], as shown in Fig. 2(a).…”

“…Both the source and the sensor are enclosed in fivelayer magnetic shield. The cell 1 [23,34,37] ventional magnetometer to detect the enhanced field. This technique takes advantage of the nuclear magnetic resonance between the modulated pseudomagnetic field B a and 129 Xe spins.…”