Barbara A. Capron

Bio: Barbara A. Capron is an academic researcher from Boeing Phantom Works. The author has contributed to research in topics: Photon & Interferometry. The author has an hindex of 5, co-authored 19 publications receiving 112 citations.

Quantum-enhanced interferometry with weak thermal light

Abstract: We propose and implement a procedure for enhancing the sensitivity with which one can determine the phase shift experienced by a thermal light beam possessing on average fewer than four photons in passing through an interferometer. Our procedure entails subtracting exactly one (which can be generalized to m) photon from the light field exiting an interferometer containing a phase-shifting element in one of its arms. As a consequence of the process of photon subtraction, the mean photon number and signal-to-noise ratio (SNR) of the resulting light field are increased, leading to an enhancement of the SNR of the interferometric signal for that fraction of the incoming data that leads to photon subtraction.

Interferometry with Photon-Subtracted Thermal Light

Abstract: We propose and implement a quantum procedure for enhancing the sensitivity with which one can determine the phase shift experienced by a weak light beam possessing thermal statistics in passing through an interferometer. Our procedure entails subtracting exactly one (which can be generalized to m) photons from the light field exiting an interferometer containing a phase-shifting element in one of its arms. As a consequence of the process of photon subtraction, and somewhat surprisingly, the mean photon number and signal-to-noise ratio of the resulting light field are thereby increased, leading to enhanced interferometry. This method can be used to increase measurement sensitivity in a variety of practical applications, including that of forming the image of an object illuminated only by weak thermal light.

Imaging with nondegenerate frequency-entangled photons

Abstract: An object that might be at least partially obscured is imaged. Frequency-entangled photons are generated. The frequency-entangled photons include photons having first and second frequencies. Those photons having the first frequency can pass through the obscuration and illuminate the object. Photons scattered by the object and those photons having the second frequency are used to form an image by considering coincidences in time of arrival.

Generation and detection of frequency entangled photons

Abstract: An ultraviolet laser generates a coherent beam, which is downconverted to produce pairs of frequency-entangled photons. For each entangled pair, a first photon is sent along a first path and a second photon is sent along a second path. A first detector detects those photons sent along the first path, and a second detector detects those photons sent along the second path. The detection is performed in a single photon regime. Coincidence counting is performed on outputs of the detectors, including comparing leading edges on outputs of the first and second detectors within a time window.

Electronic quantum information probability transfer

Abstract: Methods of digital communication utilizing entangled qubits are disclosed. The communication methods exploit selective entanglement swapping to transfer an entangled state between a sending device and a receiving device. Each device includes pairs of qubits that are independently entangled with pairs of qubits in the other device. By selectively entangling the qubits within a pair in the sending device, the qubits of the corresponding pair in the receiving device also are selectively entangled. When the qubits are entangled, they are projected onto a particular entangled state type. Though no information may be transferred through selective entanglement of one qubit pair, the disclosed methods determine whether a set of pairs of qubits are entangled by determining whether the distribution of pairs is a correlated or uncorrelated distribution (a probabilistic approach) and transform the distribution type to a classical bit of data to transfer classical bits in a qubit-efficient approach.

Quantum imaging with undetected photons

Abstract: A method comprises: generating a first and a second correlated photon beam with wavelengths λ 1 and λ 2 , respectively, wherein preferably λ 1 ≠λ 2 ; separating the first photon beam and the second photon beam; illuminating an object with the first photon beam; generating a third and a fourth correlated photon beam with wavelength λ 1 and wavelength λ 2 , respectively; overlapping the first photon beam with the third photon beam such that photons of wavelength λ 1 in either photon beam are indistinguishable; overlapping the second photon beam with the fourth photon beam such that photons of wavelength λ 2 in either photon beam are indistinguishable; and using the overlapped photons of wavelength λ 2 for imaging and/or spectroscopy of the object such that the photons that illuminate the object are not detected.

Resolving starlight: a quantum perspective

Abstract: The wave-particle duality of light introduces two fundamental problems to imaging, namely, the diffraction limit and the photon shot noise. Quantum information theory can tackle them both in one ho...

System and processor implemented method for improved image quality and generating an image of a target illuminated by quantum particles

Abstract: According to some embodiments, system and methods for image improvement comprise: receiving a plurality of frames of a given region of interest, the frames comprised of a plurality of pixels; determining, based on a quantum property of the frames, a normalized pixel intensity value for each pixel of each of the plurality of frames; and generating an improved image of the given region of interest based on the plurality of frames and the corresponding normalized pixel intensity values for the frames, the order of the image being two. Also embodiments for generating an image of a target illuminated by quantum entangled particles, such as, photons, are disclosed.

Statistics of photon-subtracted and photon-added states

Abstract: The subtraction or addition of a prescribed number of photons to a field mode does not, in general, simply shift the probability distribution by the number of subtracted or added photons. Subtraction of a photon from an initial coherent state, for example, leaves the photon statistics unchanged and the same process applied to an initial thermal state increases the mean photon number. We present a detailed analysis of the effects of the initial photon statistics on those of the state from which the photons have been subtracted or to which they have been added. Our approach is based on two closely related moment-generating functions, one that is well established and one that we introduce.

Multiphoton quantum-state engineering using conditional measurements

Abstract: The quantum theory of electromagnetic radiation predicts characteristic statistical fluctuations for light sources as diverse as sunlight, laser radiation, and molecule fluorescence. Indeed, these underlying statistical fluctuations of light are associated with the fundamental physical processes behind their generation. In this contribution, we experimentally demonstrate that the manipulation of the quantum electromagnetic fluctuations of two-mode squeezed vacuum states leads to a family of quantum-correlated multiphoton states with tunable mean photon numbers and degree of correlation. Our technique relies on the use of conditional measurements to engineer the excitation mode of the field through the simultaneous subtraction of photons from two-mode squeezed vacuum states. The experimental generation of nonclassical multiphoton states by means of photon subtraction unveils novel mechanisms to control fundamental properties of light. As a remarkable example, we demonstrate the engineering of a quantum state of light with up to ten photons, exhibiting nearly Poissonian photon statistics, that constitutes an important step towards the generation of entangled lasers. Our technique enables a robust protocol to prepare quantum states with multiple photons in high-dimensional spaces and, as such, it constitutes a novel platform for exploring quantum phenomena in mesoscopic systems.