Publications
Showing 46 results for Author: Brian P. Williams
Apr, 2025
Journal
Polarization-agnostic continuous-variable quantum key distribution
We introduce a polarization-agnostic method for Gaussian-modulated coherent-state (GCMS) continuous-variable quantum key distribution (CVQKD). Due to the random and continuous nature of the GCMS protocol, Alice, the transmitter, can encode two distinct quadratures in each of two orthogonal polarization modes, such that Bob, the receiver, measures valid GCMS quadratures in…
Apr, 2024
Journal
Field test of continuous-variable quantum key distribution with a true local oscillator
A continuous-variable quantum key distribution (CV QKD) using a true local (located at the receiver) oscillator (LO) has been proposed to remove any possibility of side-channel attacks associated with transmission of the LO as well as reduce the cross-pulse contamination. Here we report an implementation of true LO-CV QKD using “off-the-shelf” components and conduct QKD ex…
Dec, 2023
Conference Paper
Two-Photon N-Party Quantum Secret Sharing
We describe a multi-party quantum secret sharing protocol utilizing two-photon entangled states in which the source is one of the secret sharing participants. It is experimentally easier to realize than methods using GHZ states.
Dec, 2023
Conference Paper
Estimation of Optical Channel Signal Loss Following a Near-Surface Nuclear Detonation
We estimate the loss penalty for a free-space, ground to low earth orbit optical communications channel due to lofted atmospheric debris following a nuclear weapon explosion. These losses were estimated over time and compared to other loss sources like clouds and wildfire haze.
Nov, 2023
Conference Paper
Bell state optimizations for reliable quantum applications
Well-defined and stable quantum networks are essential to realize functional quantum communication applications. In particular, the quantum states must be precisely controlled to produce meaningful results. To counteract the unstable phase shifts in photonic systems, we apply local Bell state measurements to calibrate a non-local quantum channel. The calibration procedure…
Nov, 2023
ORNL Report
Milestone Completion Report for Task 2.2: Development of a raw-key based authentication scheme with security analysis & Task 2.3: Demonstrations of CV-QKD and raw-key based authentication scheme at ORNL
Quantum key distribution (QKD) allows two remote users (Alice and Bob) to establish unconditional secure cryptographic keys through an insecure channel. The generated quantum keys can be further applied in various cryptographic protocols, such as message authentication. Nevertheless, the implementation cost of a full QKD protocol is typically high. Continuous-variable (CV)…
Nov, 2023
Conference Paper
Superdense coding for quantum networking environments
Quantum networks provide a versatile infrastructure for communication, computing, and sensing with quantum information. Novel sources and detectors for transmitting and receiving quantum states are critical elements in the development and eventual deployment of robust quantum networks. Alongside performance, the compatibility of quantum network devices with modern networki…
Nov, 2023
Journal
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, connect…
Nov, 2023
Journal
A controlled-NOT gate for frequency-bin qubits
The realization of strong photon–photon interactions has presented an enduring challenge across photonics, particularly in quantum computing, where two-photon gates form essential components for scalable quantum information processing (QIP). While linear-optic schemes have enabled probabilistic entangling gates in spatio-polarization encoding, solutions for many other usef…
Nov, 2023
Journal
Quantum secret sharing with polarization-entangled photon pairs
We describe and experimentally demonstrate a more practical three-party quantum secret sharing (QSS) protocol using polarization-entangled photon pairs. The source itself serves as an active participant and can switch between the required photon states by modulating the pump beam only, thereby making the protocol less susceptible to loss and amenable to fast switching. We…
Nov, 2023
Journal
Agile frequency transformations for dense wavelength-multiplexed communications
The broad bandwidth and spectral efficiency of photonics has facilitated unparalleled speeds in long-distance lightwave communication. Yet efficient routing and control of photonic information without optical-to-electrical conversion remains an ongoing research challenge. Here, we demonstrate a practical approach for dynamically transforming the carrier frequencies of dens…