Quantum resources can enhance the sensitivity of a device beyond the classical shot noise limit and, as a result, revolutionize the field of metrology through the development of quantum-enhanced sensors In particular, plasmonic sensors, which are widely used in biological and chemical sensing applications, offer a unique opportunity to bring such an enhancement to real-life devices Here, we use bright entangled twin beams to enhance the sensitivity of a plasmonic sensor used to measure local changes in refractive index We demonstrate a 56% quantum enhancement in the sensitivity of state-of-the-art plasmonic sensor with measured sensitivities on the order of $10^{-10}$RIU$/\sqrt{\textrm{Hz}}$, nearly 5 orders of magnitude better than previous proof-of-principle implementations of quantum-enhanced plasmonic sensors These results promise significant enhancements in ultratrace label free plasmonic sensing and will find their way into areas ranging from biomedical applications to chemical detection

Quantum-Enhanced Plasmonic Sensing

Research on spatially-structured light has seen an explosion in activity over the past decades, powered by technological advances for generating such light, and driven by questions of fundamental science as well as engineering applications. In this review we highlight work on the interaction of vector light fields with atoms, and matter in general. This vibrant research area explores the full potential of light, with clear benefits for classical as well as quantum applications.

Vectorial light-matter interaction -- exploring spatially structured complex light fields

We propose a scheme to demonstrate spatiotemporal-vortex four-wave mixing (FWM) in an asymmetric semiconductor double quantum-well nanostructure. It is found that the orbital-angular-momentum (OAM) phase is transferred entirely from a unique OAM mode to the FWM field. Interestingly, by adjusting the detuning or the intensity of a control field, one can effectively modulate the phase and intensity of the FWM field. Also, we perform the superposition modes created by the interference between the FWM field and a same-frequency Laguerre-Gaussian mode, which show many interesting properties. Moreover, the conversion efficiency and quality of the output FWM field are studied. It is shown that the generated FWM mode has a maximum fidelity of approximately 100%. Our result may find potential applications in fundamental research and quantum technologies based on OAM light in solids.

Efficient spatiotemporal-vortex four-wave mixing in a semiconductor nanostructure

/pdf/coherent-light-boosted-super-sensitive-quantum-45ixscw03s.pdf

Coherent-Light Boosted, Super-Sensitive, Quantum Interferometery

Atomic Compass: Detecting 3D Magnetic Field Alignment with Vector Vortex Light

Vector beams with spatially variant polarization have attracted much attention in recent years, with potential applications in both classical optics and quantum optics. In this work, we study a polarization selection of spatial intensity distribution by utilizing a hybridly polarized beam as a coupling beam and a circularly polarized beam as a probe beam in Rb87 atom vapor. We experimentally observe that the spatial intensity distribution of the probe beam after passing through atoms can be modulated by the hybridly polarized beam due to the optical pumping effect. Then, the information loaded in the probe beam can be designedly filtrated by an atomic system with a high extinction ratio. A detailed process of the optical pumping effect in our configurations and the corresponding absorption spectra are presented to interpret our experimental results, which can be used for the spatial optical information locally extracted based on an atomic system, which has potential applications in quantum communication and computation.

Optically spatial information selection with hybridly polarized beam in atomic vapor

As a novel imaging method, ghost imaging has been widely explored in various fields of research, such as lensless ghost imaging, computational ghost imaging, turbulence-free ghost imaging. Recently, ghost imaging in non-degenerated system with pseudo-thermal light has been discussed theoretically, however, to our best knowledge, no experimental evidence has been proven yet. In this paper, we propose a new approach to realize ghost imaging with different frequencies, which are generated through a non-degenerated four-wave mixing(FWM) process in Rb vapor. In our experiment, by employing pseudo-thermal light as the probe beam, we found that the generated FWM signal has a strong second-order correlation with the original thermal light. On basis of that, we successfully implement non-degenerate ghost imaging, and reconstruct highly similar images of objects.

Ghost imaging with different frequencies through non-degenerated four-wave mixing.

In recent years, vector beams (VBs) with spatially varying polarization profiles have been used in many fields. Here we study the transmission properties of a hybrid VB passing through atomic vapor. We observe a four-petal pattern which is induced by the rapid transport of atomic coherence. This intensity distribution can be modified by coherence attenuation and absorption enhancement controlled by an external magnetic field. A second experiment with orthogonal circularly polarized states shows that the quantum coherence can be induced by two spatially separated laser beams and support our interpretation of our results for the hybrid VB experiment. Our results may have applications in optical manipulation, the measurement of magnetic fields, and the study of quantum coherence in atomic ensembles.

Observing quantum coherence induced transparency of hybrid vector beams in atomic vapor

https://iopscience.iop.org/article/10.1088/1367-2630/ab6354/pdf

Optimal phase sensitivity by quantum squeezing based on a Mach–Zehnder interferometer

According to the principle of weak measurement, when coupling the orbital angular momentum (OAM) state with a well-defined pre-selected and post-selected system of a weak measurement process, there will be an indirect coupling between position and topological charge (TC) of OAM state. Based on this we propose an experiment scheme and experimentally measure the TC of OAM beams from -14 to 14 according to the weak measurement principle. After the experiment the intrinsic OAM of the beams changed very little. Weak measurement, Topological Charge, OAM beams.

/pdf/measuring-the-topological-charge-of-orbital-angular-momentum-2yflhx7ftv.pdf

Jinwen Wang

Papers

Optically spatial information selection with hybridly polarized beam in atomic vapor

Ghost imaging with different frequencies through non-degenerated four-wave mixing.

Observing quantum coherence induced transparency of hybrid vector beams in atomic vapor

Optimal phase sensitivity by quantum squeezing based on a Mach–Zehnder interferometer

Measuring the Topological Charge of Orbital Angular Momentum Beams by Utilizing Weak Measurement Principle.