The polarization state of light is a key parameter in many imaging systems. For example, it can image mechanical stress and other physical properties that are not seen with conventional also play central role quantum sensing. However, more difficult to image, polarimetry typically involves several independent measurements moving parts the measurement device. Metasurfaces interleaved designs have demonstrated sensitivity either linear or circular/elliptical states. Here, we present an...

We demonstrate an elastically tunable self-assembled quantum dot in a nanowire antenna that emits single photons with resolution-limited spectral linewidths. The single-photon device is composed of embedded top-down fabricated waveguide integrated onto piezoelectric actuator. Nonresonant excitation leads to static (fluctuating) charges likely at the surface, causing DC Stark shifts (inhomogeneous broadening); for low powers, effects are not observed, and linewidths obtained. Despite...

Our results show a viable route to free-space quantum-secured communication in an unexplored atmospheric transparency window.

Cumulative effects are crucial for applications of laser filaments, such as the remote transfer energy and control electric discharges. Up to now, studies cumulative in air high‐repetition‐rate pulse trains have been performed at lower rates than 10 kHz. Herein, nonlinear associated with short plasma filaments produced by pulses moderate (0.4 mJ per pulse) repetition up 100 kHz experimentally characterized. With increasing rate, a decrease absorption, fluorescence emission, breakdown voltage...

We introduce an ultrasensitive interferometric protocol that combines weak value amplification (WVA) with traditional interferometry. This $\mathrm{WVA}+\text{interferometry}$ uses of the relative delay between two paths to enhance sensitivity. As example, we demonstrate a proof-of-principle experiment achieves few-attosecond timing resolution (few nanometer path length resolution) double-slit interferometer using only common optical components. Since our example spatial shift interference...

The time-resolved detection of mid- to far-infrared electric fields absorbed and emitted by molecules is among the most sensitive spectroscopic approaches has potential transform sensing in such as security screening, quality control, medical diagnostics. However, sensitivity standard approach, which relies on encoding field into amplitude modulation a visible or near-infrared probe laser pulse, limited shot noise latter. This constraint cannot be overcome without using quantum resource....

An important task for quantum-information processing is optimal discrimination between two nonorthogonal quantum states, which until now has been realized only optically. Here, we present and compare experimental realizations of measurements distinguishing states encoded in a single $^{14}\mathrm{N}$ nuclear spin at nitrogen-vacancy defect diamond. Implemented measurement schemes are the minimum-error (known as Helstrom measurement), unambiguous state using standard projective measurement,...

A semiconductor quantum dot can generate highly coherent and indistinguishable single photons. However, intrinsic dephasing mechanisms reduce the visibility of two-photon interference. For an electron in a dot, fundamental process is hyperfine interaction with nuclear spin bath. Here, we directly probe consequence fluctuating spins on elastic inelastic scattered photon spectra from resident dot. We find in-plane component Overhauser field leads to detuned Raman photons, broadened over...

A key ingredient for quantum photonic technologies is an on-demand source of indistinguishable single photons. State-of-the-art single-photon sources typically employ resonant excitation pulses with fixed repetition rates, creating a string photons predetermined arrival times. However, in future applications, independent electronic signal from larger circuit or network will trigger the generation photon. Further, operating photon up to limit imposed by its lifetime desirable. Here, we report...

The achievement of a larger magneto-optical Kerr effect (MOKE) in nanoscale layered structures is extremely important for both theoretical understandings and practical applications. However, may not always exhibit enhanced MOKE under certain geometries. In this paper, we present scheme based on weak-value amplification (WVA) simultaneously detecting enhancing the signals structures. can be effectively amplified as parameters preselection WVA. We numerically investigate dependence thickness...

We describe a method for tracking the position of small features in three dimensions from images recorded on standard microscope with an inexpensive attachment between and camera. The depth-measurement accuracy this is tested experimentally wide-field, inverted shown to give approximately 8 nm depth resolution, over specimen 6 µm, when using 12-bit charge-coupled device (CCD) camera very bright but unresolved particles. To assess low-flux limitations theoretical model used derive analytical...

We report on resonance fluorescence from a single quantum dot emitting at telecom wavelengths. perform high-resolution spectroscopy and observe the Mollow triplet in Rabi regime—a hallmark of fluorescence. The measured resonance-fluorescence spectra allow us to rule out pure dephasing as significant decoherence mechanism these dots. Combined with numerical simulations, experimental results provide robust characterisation charge noise environment dot. Resonant control opens up new...

Generalized quantum measurements are an important extension of projective or von Neumann measurements, in that they can be used to describe any measurement implemented on a system. We how realize two non-standard using cavity electrodynamics (QED). The first optimally and unabmiguously distinguishes between non-orthogonal states. second example is demonstrates superadditive coding gain. experimental tools single-atom unitary operations effected by Ramsey pulses two-atom Tavis-Cummings...

We report on the optical properties of single InAs/GaAs quantum dots emitting near telecommunication O-band, probed via Coulomb blockade and non-resonant photoluminescence spectroscopy, in presence external electric magnetic fields. extract physical electron hole wavefunctions, including confinement energies, interaction wavefunction lengths, $g$-factors. For excitons, we measure permanent dipole moment, polarizability, diamagnetic coefficient, Zeeman splitting. The carriers are determined...

By choosing more orthogonality between preselection and postselection states, one can significantly improve the sensitivity in general optical quantum metrology based on weak-value amplification (WVA) approach. However, increasing decreases probability of detecting photons makes weak measurement difficult, especially when is disturbed by strong noise pointer drowned with a negative-decibel signal-to-noise ratio (SNR). In this article we introduce numerically evaluate modified...

Owing to a reduced solar background and low propagation losses in the atmosphere, 2- 2.5-$\mu$m waveband is promising candidate for daylight quantum communication. This spectral region also offers dispersion hollow-core fibers silicon waveguides. We demonstrate first time near-maximally entangled photon pairs at 2.1 $\mu$m that could support device independent key distribution (DIQKD) assuming sufficiently high channel efficiencies. The state corresponds positive secure-key rate (0.254...

Quantum correlations resulting in violations of Bell inequalities have generated a lot interest quantum information science and fundamental physics. In this paper, we address some questions that become relevant Bell-type tests involving systems with local dimension greater than 2. For CHSH-Bell within 2D subspaces such high-dimensional systems, it has been suggested experimental violation Tsirelson's bound indicates more entanglement was present. We explain the overstepping is due to fair...

Electro-optical sampling of Terahertz fields with ultrashort pulsed probes is a well-established approach for directly measuring the electric field THz radiation. This technique usually relies on balanced detection to record optical phase shift brought by THz-induced birefringence. The sensitivity electro-optical is, therefore, limited shot noise probe pulse, and improvements could be achieved using quantum metrology approaches using, e.g., NOON states Heisenberg-limited estimation. We...

We introduce an ultra-sensitive interferometric protocol that combines weak value amplification (WVA) with traditional interferometry. This WVA+interferometry uses of the relative delay between two paths to enhance sensitivity, approaching quantum limit for classical light. As example, we demonstrate a proof-of-principle experiment achieves few-attosecond timing resolution (few-nanometer path length resolution) double-slit interferometer using only common optical components. Since our...

Advancements in quantum communication and sensing require improved optical transmission that ensures excellent state purity reduced losses. While free-space is often preferred, its use becomes challenging over long distances due to beam divergence, atmospheric absorption, scattering, turbulence, among other factors. In the case of polarization encoding, traditional silica-core fibers, though commonly used, struggle with maintaining stress-induced birefringence. Hollow core particular nested...

Advancements in quantum communication and sensing require improved optical transmission that ensures excellent state purity reduced losses. While free-space is often preferred, its use becomes challenging over long distances due to beam divergence, atmospheric absorption, scattering, turbulence, among other factors. In the case of polarization encoding, traditional silica-core fibers, though commonly used, struggle with maintaining stress-induced birefringence. Hollow core particular nested...

Advancements in quantum communication and sensing require improved optical transmission that ensures excellent state purity reduced losses. While free-space is often preferred, its use becomes challenging over long distances due to beam divergence, atmospheric absorption, scattering, turbulence, among other factors. In the case of polarization encoding, traditional silica-core fibers, though commonly used, struggle with maintaining stress-induced birefringence. Hollow core particular nested...

Advancements in quantum communication and sensing require improved optical transmission that ensures excellent state purity reduced losses. While free-space is often preferred, its use becomes challenging over long distances due to beam divergence, atmospheric absorption, scattering, turbulence, among other factors. In the case of polarization encoding, traditional silica-core fibers, though commonly used, struggle with maintaining stress-induced birefringence. Hollow core particular nested...

Joint or simultaneous measurements of non-commuting quantum observables are possible at the cost increased unsharpness measurement uncertainty.Many different criteria exist for defining what an "optimal" joint is, with corresponding tradeoff relations measurements.Understanding limitations such is fundamental interest and relevant technology.Here, we experimentally test a relation sharpness qubit measurements, which refers directly to form operators, rather than errors in estimates.We...