Ultrasensitive magnetic field detection using a single artificial atom

Abstract

Efficient detection of magnetic fields is central to many areas of research and technology. High-sensitivity detectors are commonly built using direct-current superconducting quantum interference devices or atomic systems. Here we use a single artificial atom to implement an ultrasensitive magnetometer with micron range size. The artificial atom, a superconducting two-level system, is operated similarly to atom and diamond nitrogen-vacancy centre-based magnetometers. The high sensitivity results from quantum coherence combined with strong coupling to magnetic field. We obtain a sensitivity of 3.3 pT Hz À 1/2 for a frequency of 10 MHz. We discuss feasible improvements to increase sensitivity by one order of magnitude. The intrinsic sensitivity of this detector at frequencies in the 100 kHz-10 MHz range compares favourably with direct-current superconducting quantum interference devices and atomic magnetometers of equivalent spatial resolution. This result illustrates the potential of artificial quantum systems for sensitive detection and related applications.

Realizing a Circuit Analog of an Optomechanical System with Longitudinally Coupled Superconducting Resonators

“…Our results pave the way towards the exploration of optomechanical effects in a fully superconducting platform and could enable quantum optics experiments with photons in the yet unexplored radio frequency band.Circuit quantum electrodynamics (cQED) has become one of the primary platforms used to experimentally explore fundamental aspects of quantum physics [1][2][3][4], build practical devices for sensitive measurements [5][6][7][8][9], and eventually realize fault tolerant quantum computers [10][11][12][13][14]. The versatility in the design and fabrication of these circuits has also enabled their efficient coupling to other quantized degrees of freedom such as spins and charges in semiconductors [15][16][17][18][19][20][21] and mechanical resonators [22][23][24][25], as well as their use for the sensing of electromagnetic noise [26][27][28][29].Individual elements in cQED devices, such as resonators and qubits, are most commonly coupled to each other through field-field or dipole-field interactions, which typically result in Jaynes-Cummings-type coupling Hamiltonians of the form H int ∼ a † b + ab † , where a (b) and a † (b † ) are annihilation and creation operators of the two coupled modes, respectively. Such couplings are also referred to as transversal couplings [30], relating the orientation of the qubit dipole operator to the quantization axis defined by the uncoupled qubit eigenstates.…”

A hybrid-systems approach to spin squeezing using a highly dissipative ancillary system

“…with effective Hamiltonian and Lindblad operatorŝˆ[ˆ(ˆ) Comparison of the proposed spin squeezed magnetometer (the black star; based on a flux qubit and donor spins implementation) with reported values for existing devices[52][53][54][55][56][57][58][59][60][61][62][63][64].…”

Superharmonic resonances in a strongly coupled cavity-atom system

“…In this study we investigate the driven dynamics of a strongly interacting system composed of a superconducting flux qubit [15,16] and a coplanar waveguide (CPW) microwave cavity [9,14,[17][18][19][20][21]. The nonlinear cavity response [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] is measured as a function of the magnetic flux that is applied to the qubit.…”

“…Attenuators and filters are installed at different cooling stages along the transmission lines for qubit control and readout. A detailed description of sample fabrication and experimental setup can be found in [14,18].…”