



@article {3408,
	title = {A general approach to backaction-evading receivers with magnetomechanical and electromechanical sensors},
	year = {2023},
	month = {11/16/2023},
	abstract = {<p>Today\&$\#$39;s mechanical sensors are capable of detecting extremely weak perturbations while operating near the standard quantum limit. However, further improvements can be made in both sensitivity and bandwidth when we reduce the noise originating from the process of measurement itself -- the quantum-mechanical backaction of measurement -- and go below this \&$\#$39;standard\&$\#$39; limit, possibly approaching the Heisenberg limit. One of the ways to eliminate this noise is by measuring a quantum nondemolition variable such as the momentum in a free-particle system. Here, we propose and characterize theoretical models for direct velocity measurement that utilize traditional electric and magnetic transducer designs to generate a signal while enabling this backaction evasion. We consider the general readout of this signal via electric or magnetic field sensing by creating toy models analogous to the standard optomechanical position-sensing problem, thereby facilitating the assessment of measurement-added noise. Using simple models that characterize a wide range of transducers, we find that the choice of readout scheme -- voltage or current -- for each mechanical detector configuration implies access to either the position or velocity of the mechanical sub-system. This in turn suggests a path forward for key fundamental physics experiments such as the direct detection of dark matter particles.</p>},
	url = {https://arxiv.org/abs/2311.09587},
	author = {Brittany Richman and Sohitri Ghosh and Daniel Carney and Gerard Higgins and Peter Shawhan and C. J. Lobb and Jacob M. Taylor}
}
@article {2684,
	title = {Circulation by microwave-induced vortex transport for signal isolation},
	journal = {PRX Quantum},
	volume = {2},
	year = {2021},
	month = {6/14/2021},
	pages = {030309},
	abstract = {<p>Magnetic fields break time-reversal symmetry, which is leveraged in many settings to enable the nonreciprocal behavior of light. This is the core physics of circulators and other elements used in a variety of microwave and optical settings. Commercial circulators in the microwave domain typically use ferromagnetic materials and wave interference, requiring large devices and large fields. However, quantum information devices for sensing and computation require small sizes, lower fields, and better on-chip integration. Equivalences to ferromagnetic order---such as the XY model---can be realized at much lower magnetic fields by using arrays of superconducting islands connected by Josephson junctions. Here we show that the quantum-coherent motion of a single vortex in such an array suffices to induce nonreciprocal behavior, enabling a small-scale, moderate-bandwidth, and low insertion loss circulator at very low magnetic fields and at microwave frequencies relevant for experiments with qubits.</p>},
	doi = {https://doi.org/10.1103/PRXQuantum.2.030309},
	url = {https://arxiv.org/abs/2010.04118},
	author = {Brittany Richman and J. M. Taylor}
}
