1,817 research outputs found
Experimental generation of an optical field with arbitrary spatial coherence properties
We describe an experimental technique to generate a quasi-monochromatic field
with any arbitrary spatial coherence properties that can be described by the
cross-spectral density function, . This is done by using a
dynamic binary amplitude grating generated by a digital micromirror device
(DMD) to rapidly alternate between a set of coherent fields, creating an
incoherent mix of modes that represent the coherent mode decomposition of the
desired . This method was then demonstrated experimentally
by interfering two plane waves and then spatially varying the coherent between
these two modes such that the interference fringe visibility was shown to vary
spatially between the two beams in an arbitrary and prescribed way.Comment: 6 pages, 5 figur
Quantum-secured imaging
We have built an imaging system that uses a photon's position or
time-of-flight information to image an object, while using the photon's
polarization for security. This ability allows us to obtain an image which is
secure against an attack in which the object being imaged intercepts and
resends the imaging photons with modified information. Popularly known as
"jamming," this type of attack is commonly directed at active imaging systems
such as radar. In order to jam our imaging system, the object must disturb the
delicate quantum state of the imaging photons, thus introducing statistical
errors that reveal its activity.Comment: 10 pages (double spaced), 5 figure
State transfer based on classical nonseparability
We present a state transfer protocol that is mathematically equivalent to
quantum teleportation, but uses classical nonseparability instead of quantum
entanglement. In our implementation we take advantage of nonseparability among
three parties: orbital angular momentum (OAM), polarization, and the radial
degrees of freedom of a beam of light. We demonstrate the transfer of arbitrary
OAM states, in the subspace spanned by any two OAM states, to the polarization
of the same beam
Multiplexing Free-Space Channels using Twisted Light
We experimentally demonstrate an interferometric protocol for multiplexing
optical states of light, with potential to become a standard element in
free-space communication schemes that utilize light endowed with orbital
angular momentum (OAM). We demonstrate multiplexing for odd and even OAM
superpositions generated using different sources. In addition, our technique
permits one to prepare either coherent superpositions or statistical mixtures
of OAM states. We employ state tomography to study the performance of this
protocol, and we demonstrate fidelities greater than 0.98.Comment: 4 pages, 3 figure
Compressive Object Tracking using Entangled Photons
We present a compressive sensing protocol that tracks a moving object by
removing static components from a scene. The implementation is carried out on a
ghost imaging scheme to minimize both the number of photons and the number of
measurements required to form a quantum image of the tracked object. This
procedure tracks an object at low light levels with fewer than 3% of the
measurements required for a raster scan, permitting us to more effectively use
the information content in each photon.Comment: 10 pages, 4 figure
Latinx/Chicanx Students on the Path to Conocimiento: Critical Reflexivity Journals as Tools for Healing and Resistance in the Trump Era
Anzaldúa’s concept of conocimiento guides our analysis of Latinx/Chicanx students’ Critical Reflexivity Journals (CRJ) produced in an Ethnic Studies classroom at a predominantly-white institution. Through a thematic analysis procedure of students’ CRJ entries, which we describe as written testimonios, we discerned how Latinx/Chicanx students’ writings engaged their identities, reflexivity, healing, and resistance on a path toward conocimiento. Grounding our theoretical and empirical analysis in Anzaldúan thought, conocimiento is characterized by a deep reflexive critical consciousness that unfolds across seven interconnected stages. Conocimiento builds toward a liberatory transformation that Anzaldúa describes as spiritual activism, the seventh and final stage of conocimiento. The sociohistorical, culturally relevant, and studentcentered curricula purported in Ethnic Studies is the focus of much scholarly writings. Our work contributes to this growing theoretical, empirical and pedagogical scholarship by specifically focusing on conocimiento. Through an Anzaldúa centered analysis of Latinx/Chicanx students’ CRJ we demonstrate how reflexive writings can facilitate students’ process of identity formation, reflexivity, healing and resistance from colonial forms of knowledge and oppression. This is especially important when considering the racist and violent sociopolitical context under the Trump Administration
Measurement of the Photon-Plasmon Coupling Phase
Scattering processes have played a crucial role in the development of quantum
theory. In the field of optics, scattering phase shifts have been utilized to
unveil interesting forms of light-matter interactions. Here, we investigate the
mode-coupling phase of single photons to surface plasmon polaritons in a
quantum plasmonic tritter. We observe that the coupling process induces a phase
jump that occurs when photons scatter into surface plasmons and vice versa.
This interesting coupling phase dynamics is of particular relevance for quantum
plasmonic experiments. Furthermore, it is demonstrated that this photon-plasmon
interaction can be modeled through a quantum-mechanical tritter. We show that
the visibility of a double-slit and a triple-slit interference patterns are
convenient observables to characterize the interaction at a slit and determine
the coupling phase. Our accurate and simple model of the interaction, validated
by simulations and experiments, has important implications not only for quantum
plasmonic interference effects, but is also advantageous to classical
applications
Quantum Hilbert hotel
In 1924 David Hilbert conceived a paradoxical tale involving a hotel with an infinite number of rooms to illustrate some aspects of the mathematical notion of “infinity.” In continuous-variable quantum mechanics we routinely make use of infinite state spaces: here we show that such a theoretical apparatus can accommodate an analog of Hilbert’s hotel paradox. We devise a protocol that, mimicking what happens to the guests of the hotel, maps the amplitudes of an infinite eigenbasis to twice their original quantum number in a coherent and deterministic manner, producing infinitely many unoccupied levels in the process. We demonstrate the feasibility of the protocol by experimentally realizing it on the orbital angular momentum of a paraxial field. This new non-Gaussian operation may be exploited, for example, for enhancing the sensitivity of NOON states, for increasing the capacity of a channel, or for multiplexing multiple channels into a single one
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