arXiv subjects

B. J. Lawrie

Publications and source records attributed to B. J. Lawrie.

7 recordsLinked to original sources

arXiv2021

Free-space confocal magneto-optical spectroscopies at milliKelvin temperatures

We describe the operation of a free-space confocal optical microscope operated in a dilution refrigerator. The microscope is installed on a cold insertable probe to enable fast sample exchange while the refrigerator is held at low temperatures. A vector magnet provides a 6 T field normal to the sample and 1 T fields at arbitrary angles. A variety of optical microscopies and spectroscopies, including photoluminescence, Raman, magneto-optical Kerr effect, and spin relaxometry measurements are described, and some of the challenges associated with performing these measurements at milliKelvin temperatures are explored.

quant-ph↗

arXiv2019

Truncated nonlinear interferometry for quantum enhanced atomic force microscopy

Nonlinear interferometers that replace beamsplitters in Mach-Zehnder interferometers with nonlinear amplifiers for quantum-enhanced phase measurements have drawn increasing interest in recent years, but practical quantum sensors based on nonlinear interferometry remain an outstanding challenge. Here, we demonstrate the first practical application of nonlinear interferometry by measuring the displacement of an atomic force microscope microcantilever with quantum noise reduction of up to 3~dB below the standard quantum limit, corresponding to a quantum-enhanced measurement of beam displacement of $\mathrm{1.7~fm/\sqrt{Hz}}$. Further, we show how to minimize photon backaction noise while taking advantage of quantum noise reduction by transducing the cantilever displacement signal with a weak squeezed state while using dual homodyne detection with a higher power local oscillator. This approach offers a path toward quantum-enhanced broadband, high-speed scanning probe microscopy.

quant-ph↗

arXiv2015

Ultrasensitive measurement of MEMS cantilever displacement sensitivity below the shot noise limit

The displacement of micro-electro-mechanical-systems (MEMS) cantilevers is used to measure a broad variety of phenomena in devices ranging from force microscopes to biochemical sensors to thermal imaging systems. We demonstrate the first direct measurement of a MEMS cantilever displacement with a noise floor at 40% of the shot noise limit (SNL). By combining multi-spatial-mode quantum light sources with a simple differential measurement, we show that sub-SNL MEMS displacement sensitivity is highly accessible compared to previous efforts that measured the displacement of macroscopic mirrors with very distinct spatial structures crafted with multiple optical parametric amplifiers and locking loops. These results support a new class of quantum MEMS sensor with an ultimate signal to noise ratio determined by quantum correlations, enabling ultra-trace sensing, imaging, and microscopy applications in which signals were previously obscured by shot noise.

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arXiv2014

Coherence area profiling in multi-spatial-mode squeezed states

The presence of multiple bipartite entangled modes in squeezed states generated by four wave mixing in atomic vapors enables ultra-trace sensing, imaging, and metrology applications that are impossible to achieve with single-spatial-mode squeezed states. For Gaussian seed beams, the spatial distribution of bipartite entangled modes, or coherence areas, across each beam is largely dependent on the spatial modes present in the pump beam, but it has proven difficult to map the distribution of these coherence areas in frequency and space. We demonstrate an accessible method to map the distribution of the coherence areas within these twin beams. We also show that the pump shape can impart different noise properties to each coherence area, and that it is possible to select and detect coherence areas with optimal squeezing with this approach.

quant-ph↗

arXiv2014

Nonlinear optical magnetometry with accessible in situ optical squeezing

We demonstrate compact and accessible squeezed-light magnetometry using four-wave mixing in a single hot rubidium vapor cell. The strong intrinsic coherence of the four wave mixing process results in nonlinear magneto-optical rotation (NMOR) on each mode of a two mode relative-intensity squeezed state. This framework enables 4.7 dB of quantum noise reduction while the opposing polarization rotation signals of the probe and conjugate fields add to increase the total signal to noise ratio.

quant-ph↗

arXiv2013

Extraordinary optical transmission of multimode quantum correlations via localized surface plasmons

We demonstrate the coherent transduction of quantum noise reduction, or squeezed light, by Ag localized surface plasmons (LSPs). Squeezed light, generated through four-wave-mixing in Rb vapor, is coupled to a Ag nanohole array designed to exhibit LSP-mediated extraordinary-optical transmission (EOT) spectrally coincident with the squeezed light source at 795 nm. We demonstrate that quantum noise reduction as a function of transmission is found to match closely with linear attenuation models, thus demonstrating that the photon-LSP-photon transduction process is coherent near the LSP resonance.

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arXiv2013

Toward real-time quantum imaging with a single pixel camera

We present a workbench for the study of real-time quantum imaging by measuring the frame-by-frame quantum noise reduction of multi-spatial-mode twin beams generated by four wave mixing in Rb vapor. Exploiting the multiple spatial modes of this squeezed light source, we utilize spatial light modulators to selectively pass macropixels of quantum correlated modes from each of the twin beams to a high quantum efficiency balanced detector. In low-light-level imaging applications, the ability to measure the quantum correlations between individual spatial modes and macropixels of spatial modes with a single pixel camera will facilitate compressive quantum imaging with sensitivity below the photon shot noise limit.

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