arXiv subjects

Martin Plenio

Publications and source records attributed to Martin Plenio.

3 recordsLinked to original sources

arXiv2020

On the robustness of the NV-NMR spectrometer setup to magnetic field inhomogeneities

The NV-NMR spectrometer is a promising candidate for detection of NMR signals at the nano scale. Field inhomogeneities, however, are a major source of noise that limits spectral resolution in state of the art NV - NMR experiments and constitutes a major bottleneck in the development of nano scale NMR. Here we propose, a route in which this limitation could be circumvented in NV-NMR spectrometer experiments, by utilising the nanometric scale and the quantumness of the detector.

quant-ph↗

arXiv2017

Sub-millihertz magnetic spectroscopy with a nanoscale quantum sensor

Precise timekeeping is critical to metrology, forming the basis by which standards of time, length and fundamental constants are determined. Stable clocks are particularly valuable in spectroscopy as they define the ultimate frequency precision that can be reached. In quantum metrology, where the phase of a qubit is used to detect external fields, the clock stability is defined by the qubit coherence time, which determines the spectral linewidth and frequency precision. Here we demonstrate a quantum sensing protocol where the spectral precision goes beyond the sensor coherence time and is limited by the stability of a classical clock. Using this technique, we observe a precision in frequency estimation scaling in time $T$, as $T^{-3/2}$ for classical oscillating fields. The narrow linewidth magnetometer based on single spins in diamond is used to sense nanoscale magnetic fields with an intrinsic frequency resolution of 607 $μ$Hz, 8 orders of magnitude narrower than the qubit coherence time.

quant-ph↗

arXiv2007

Stochastic Resonance Phenomena in Quantum Many-Body Systems

We discuss stochastic resonance (SR) effects in driven coupled quantum systems. We construct dynamical and information theoretic measures of the system's response that exhibit a non-monotonic behaviour as a function of the noise strength. We analyze the relation between lack of monotonicity in the response and the presence of quantum correlations and identify parameter regimes where the breakdown of a linear response can be linked to the presence of entanglement. We also show that a chain of coupled spin systems can exhibit an array-enhanced response, where the sensitivity of a single resonator is enhanced as a result of nearest-neighbour coupling. These results enlarge the domain where SR effects exist and should be observable in arrays of superconducting qubits.

quant-ph↗