Quantum enhanced distributed phase sensing with a truncated SU(1,1) interferometer

In recent years, distributed quantum sensing has gained interest for a range of applications requiring networks of sensors, from global-scale clock synchronization to high energy physics. In particular, a network of entangled sensors can improve not only the sensitivity beyond the shot noise limit, but also enable a Heisenberg scaling with the number of sensors. Here, using bright entangled twin beams, we theoretically and experimentally demonstrate the detection of a linear combination of two distributed phases beyond the shot noise limit with a truncated SU(1,1) interferometer. We experimentally demonstrate a quantum noise reduction of 1.7 dB and a classical 3 dB signal-to-noise ratio improvement over the separable sensing approach involving two truncated SU(1,1) interferometers. Additionally, we theoretically extend the use of a truncated SU(1,1) interferometer to a multi-phase-distributed sensing scheme that leverages entanglement as a resource to achieve a quantum improvement in the scaling with the number of sensors in the network. Our results pave the way for developing quantum enhanced sensor networks that can achieve an entanglement-enhanced sensitivity

A Reconfigurable Quantum Local Area Network Over Deployed Fiber

Practical quantum networking architectures are crucial for scaling the connection of quantum resources. Yet quantum network testbeds have thus far underutilized the full capabilities of modern lightwave communications, such as flexible-grid bandwidth allocation. In this work, we implement flex-grid entanglement distribution in a deployed network for the first time, connecting nodes in three distinct campus buildings time-synchronized via the Global Positioning System (GPS). We quantify the quality of the distributed polarization entanglement via log-negativity, which offers a generic metric of link performance in entangled bits per second. After demonstrating successful entanglement distribution for two allocations of our eight dynamically reconfigurable channels, we demonstrate remote state preparation -- the first realization on deployed fiber -- showcasing one possible quantum protocol enabled by the distributed entanglement network. Our results realize an advanced paradigm for managing entanglement resources in quantum networks of ever-increasing complexity and service demands

Searching For Dark Matter with Plasma Haloscopes

We summarise the recent progress of the Axion Longitudinal Plasma HAloscope (ALPHA) Consortium, a new experimental collaboration to build a plasma haloscope to search for axions and dark photons. The plasma haloscope is a novel method for the detection of the resonant conversion of light dark matter to photons. ALPHA will be sensitive to QCD axions over almost a decade of parameter space, potentially discovering dark matter and resolving the Strong CP problem. Unlike traditional cavity haloscopes, which are generally limited in volume by the Compton wavelength of the dark matter, plasma haloscopes use a wire metamaterial to create a tuneable artificial plasma frequency, decoupling the wavelength of light from the Compton wavelength and allowing for much stronger signals. We develop the theoretical foundations of plasma haloscopes and discuss recent experimental progress. Finally, we outline a baseline design for ALPHA and show that a full-scale experiment could discover QCD axions over almost a decade of parameter space.Comment: Endorsers: Jens Dilling, Michael Febbraro, Stefan Knirck, and Claire Marvinney. 26 pages, 17 figures, version accepted in Physical Review

Effect of Material Structure on Photoluminescence of ZnO/MgO Core-Shell Nanowires

Zinc oxide (ZnO) nanowires are widely studied for use in ultraviolet optoelectronic devices, such as nanolasers and sensors. Nanowires (NWs) with an MgO shell exhibit enhanced band-edge photoluminescence (PL), a result previously attributed to passivation of ZnO defects. However, we find that processing the ZnO NWs under low oxygen partial pressure leads to an MgO-thickness-dependent PL enhancement owing to the formation of optical cavity modes. Conversely, processing under higher oxygen partial pressure leads to NWs that support neither mode formation nor band-edge PL enhancement. High-resolution electron microscopy and density-functional calculations implicate the ZnO m-plane surface morphology as the key determinant of core-shell structure and cavity-mode optics. A ZnO surface with atomic steps along the m-plane in the c-axis direction stimulates the growth of a smooth MgO shell that supports guided-wave optical modes and enhanced UV PL. On the other hand, a smoother ZnO surface leads to nucleation of a rough cladding layer which supports neither enhanced UV PL nor optical cavity modes. Finite-element analysis shows a clear correlation between allowed Fabry-Perot and whispering gallery modes and enhanced UV-PL. These results point the way to fabricating ZnO/MgO core-shell nanowires for more efficient UV nanolasers, scintillators, and sensors

Advanced architectures for high-performance quantum networking

As practical quantum networks prepare to serve an ever-expanding number of nodes, there has grown a need for advanced auxiliary classical systems that support the quantum protocols and maintain compatibility with the existing fiber-optic infrastructure. We propose and demonstrate a quantum local area network design that addresses current deployment limitations in timing and security in a scalable fashion using commercial off-the-shelf components. We employ White Rabbit switches to synchronize three remote nodes with ultra-low timing jitter, significantly increasing the fidelities of the distributed entangled states over previous work with Global Positioning System clocks. Second, using a parallel quantum key distribution channel, we secure the classical communications needed for instrument control and data management. In this way, the conventional network which manages our entanglement network is secured using keys generated via an underlying quantum key distribution layer, preserving the integrity of the supporting systems and the relevant data in a future-proof fashion.Comment: 7 pages, 4 figure