133 research outputs found
Characterization of Quantum Frequency Processors
Frequency-bin qubits possess unique synergies with wavelength-multiplexed
lightwave communications, suggesting valuable opportunities for quantum
networking with the existing fiber-optic infrastructure. Although the coherent
manipulation of frequency-bin states requires highly controllable
multi-spectral-mode interference, the quantum frequency processor (QFP)
provides a scalable path for gate synthesis leveraging standard telecom
components. Here we summarize the state of the art in experimental QFP
characterization. Distinguishing between physically motivated ''open box''
approaches that treat the QFP as a multiport interferometer, and ''black box''
approaches that view the QFP as a general quantum operation, we highlight the
assumptions and results of multiple techniques, including quantum process
tomography of a tunable beamsplitter -- to our knowledge the first full process
tomography of any frequency-bin operation. Our findings should inform future
characterization efforts as the QFP increasingly moves beyond
proof-of-principle tabletop demonstrations toward integrated devices and
deployed quantum networking experiments
How Do Test Takers Interact With Simulation-Based Tasks? A Response-Time Perspective
Many traditional educational assessments use multiple-choice items and constructed-response items to measure fundamental skills. Virtual performance assessments, such as game- or simulation-based assessments, are designed recently in the field of educational measurement to measure more integrated skills through the test takers’ interactive behaviors within an assessment in a virtual environment. This paper presents a systematic timing study based on data collected from a simulation-based task designed recently at Educational Testing Service. The study is intended to understand the response times in complex simulation-based tasks so as to shed light on possible ways of leveraging response time information in designing, assembling, and scoring of simulation-based tasks. To achieve this objective, a series of five analyses were conducted to first understand the statistical properties of the timing data, and then investigate the relationship between the timing patterns and the test takers’ performance on the items/task, demographics, motivation level, personality, and test-taking behaviors through use of different statistical approaches. We found that the five analyses complemented each other and revealed different useful timing aspects of this test-taker sample’s behavioral features in the simulation-based task. The findings were also compared with notable existing results in the literature related to timing data
Two-mode squeezing over deployed fiber coexisting with conventional communications
Squeezed light is a crucial resource for continuous-variable (CV) quantum
information science. Distributed multi-mode squeezing is critical for enabling
CV quantum networks and distributed quantum sensing. To date, multi-mode
squeezing measured by homodyne detection has been limited to single-room
experiments without coexisting classical signals, i.e., on ``dark'' fiber.
Here, after distribution through separate fiber spools (5~km), -dB
coexistent two-mode squeezing is measured. Moreover, after distribution through
separate deployed campus fibers (about 250~m and 1.2~km), -dB
coexistent two-mode squeezing is measured. Prior to distribution, the squeezed
modes are each frequency multiplexed with several classical signals --
including the local oscillator and conventional network signals --
demonstrating that the squeezed modes do not need dedicated dark fiber. After
distribution, joint two-mode squeezing is measured and recorded for
post-processing using triggered homodyne detection in separate locations. This
demonstration enables future applications in quantum networks and quantum
sensing that rely on distributed multi-mode squeezing.Comment: 23 pages, 13 figures, 2 table
Generation and characterization of ultrabroadband polarization-frequency hyperentangled photons
We generate ultrabroadband photon pairs entangled in both polarization and
frequency bins through an all-waveguided Sagnac source covering the entire
optical C- and L-bands (1530--1625 nm). We perform comprehensive
characterization of high-fidelity states in multiple dense wavelength-division
multiplexed channels, achieving full tomography of effective four-qubit
systems. Additionally, leveraging the inherent high dimensionality of frequency
encoding and our electro-optic measurement approach, we demonstrate the
scalability of our system to higher dimensions, reconstructing states in a
36-dimensional Hilbert space consisting of two polarization qubits and two
frequency-bin qutrits. Our findings hold potential significance for quantum
networking, particularly dense coding and entanglement distillation in
wavelength-multiplexed quantum networks
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