Experimental demonstration of long distance quantum communication with independent heralded single photon sources

Demonstration of long distance MDI-QKD quantum communication

Researchers achieved a breakthrough in quantum communication by using common laser pulses to generate intrinsically synchronized single photons, eliminating time jitter issues and achieving coincidence rates over 100 times higher than previous methods across 50km of fiber, enabling practical measurement-device-independent quantum key distribution.

RF heterodyne detection of squeezed light.

Digital reconstruction of squeezed light for quantum information processing

Squeezed light enables advanced quantum applications but faces practical challenges that the authors address through a novel radio-frequency heterodyne detection method with digital unitary transformations, successfully demonstrated over fiber channels for quantum key distribution and sensing networks without requiring complex stabilization systems.

Quantum teleportation with nonlinear sum frequency generation (SFG). The nonlinear nanophotonic platform greatly mitigates multiphoton noise and leads to high teleportation fidelity. Credit: The Grainger College of Engineering at the University of Illinois Urbana-Champaign

Quantum Leap: Nanophotonics Revolutionizes Teleportation

Researchers at the University of Illinois Urbana-Champaign have achieved a breakthrough in quantum teleportation by using an indium-gallium-phosphide nanophotonic platform that dramatically improves quantum information transmission to 94% fidelity (compared to the theoretical limit of 33% with conventional methods), bringing practical quantum communication networks closer to reality.

Steering nonlocality in high-speed telecommunication system without detection loophole - Experimental setup.

Steering nonlocality in high-speed telecommunication system without detection loophole

Researchers achieved the first detection-loophole-free quantum steering demonstration in a fully integrated chip-fiber telecommunication system, using innovative phase-encoding measurements and a custom low-loss silicon chip to enable an unprecedented 1.25 GHz switching rate, marking a significant advancement toward practical quantum communication applications.

Photoluminescent excitation spectrum of Er3+ ions in silicon.

Long optical and electron spin coherence times for erbium ions in silicon

Erbium ions in silicon demonstrate unprecedented coherence properties with optical linewidths below 70 kHz and electron spin coherence times exceeding 0.8 ms, establishing a promising telecommunications-compatible platform for quantum information processing that leverages existing silicon nanofabrication technologies.

Frequency-bin entanglement-based Quantum Key Distribution: Experimental setup and device spectra.

Frequency-bin entanglement-based Quantum Key Distribution

The researchers demonstrated the first complete implementation of entanglement-based quantum key distribution using frequency-bin encoding on a silicon photonic chip, overcoming phase noise challenges to achieve stable transmission over 26 kilometers of fiber with a secure key rate of at least 4.5 bits per second.

ORNL scientists successfully combined key quantum photonic capabilities on a single chip for the first time. Credit: ORNL, U.S. Dept. of Energy

Silicon Chip Breakthrough: Quantum Photonics for Fiber Networks

Silicon photonic integrated circuit developed by ORNL scientists combines a bidirectionally pumped microring resonator with polarization splitter-rotators to generate broadband, high-fidelity polarization-entangled photons across 116 frequency-bin pairs compatible with existing fiber-optic networks, marking a significant advancement toward a scalable quantum internet.

Setup of free-space CV-QKD

Robust Continuous-Variable Quantum Key Distribution in Daylight Conditions

The research demonstrates a breakthrough Gaussian modulated coherent state continuous-variable quantum key distribution system that operates effectively in daylight and rainy conditions over an 860-meter free-space link, achieving high secure key rates without complex filtering by using a 1550 nm wavelength and polarization-multiplexed local oscillator, significantly advancing practical quantum communication applications.

Minimum cost flow.

Networking quantum networks with minimum cost aggregation

A quantum internet protocol using minimum cost aggregation and network concatenation enables efficient distribution of entangled bits with bounded error between arbitrary clients across multiple quantum networks regardless of distance, overcoming previous limitations and forming the necessary foundation for global-scale quantum networking.

QIA researchers create first Operating System for Quantum Networks

QNodeOS: Revolutionizing Quantum Networks

Researchers from the Quantum Internet Alliance have created QNodeOS, the first operating system for quantum networks, which abstracts hardware complexity to enable easier development of quantum networking applications across different hardware platforms, marking a crucial step toward making quantum internet technology accessible and practical.

Boosted quantum teleportation - Schematic of the experimental set-up.

Breaking Barriers in Quantum Teleportation

Researchers have achieved a breakthrough in quantum teleportation by using ancillary photonic states to surpass the 50% Bell-state measurement success probability limit of linear optics, demonstrating an impressive 69.71% acceptance rate with high fidelity (0.8677) on arbitrary input states from independent sources, representing the first practical implementation of Boosted Quantum Teleportation with significant implications for quantum repeaters, communications, and computation.

Schematic of a quantum network link based on multiple 171Yb qubits in nanophotonic cavities.

Multi-Qubit Nodes Expands Quantum Network Potential

Researchers have achieved a breakthrough in quantum networking by creating a two-node system with multiple rare-earth ions per node that enables multiplexed entanglement distribution and multipartite state preparation, overcoming traditional single-qubit limitations and laying the groundwork for scalable quantum networks with applications in computing, communication, and sensing.

IonQ to acquire ID Quantique to form the world’s largest quantum-safe networks and quantum networking provider

IonQ to Acquire Controlling Stake in ID Quantique

IonQ is acquiring a controlling stake in quantum safe networking leader ID Quantique (IDQ) to strengthen its global quantum ecosystem, accelerate quantum networking development, and establish a strategic partnership with SK Telecom, with the acquisition expected to close in Q2 2025.

Anahita Khodadad Kashi and Prof. Dr. Michael Kues demonstrated for the first time entanglement-based quantum key distribution using the frequency degree of freedom to enable scalable quantum networks. Credit: Leibniz University Hannover

Light-Based Quantum Networks: A Breakthrough in Secure Data

Scientists at Leibniz University Hannover have developed a cost-effective quantum network security system using frequency-bin coding of light particles, which reduces complexity and equipment costs by 75% while enhancing security against quantum computer threats through a simplified single-detector design that enables dynamic, scalable quantum key distribution.

Oak Ridge National Laboratory collaborated with commercial utility EPB and the University of Tennessee Chattanooga to develop and test the first transmission of an entangled quantum signal using multiple wavelength channels and automatic polarization stabilization over a commercial network with no downtime. Credit: Morgan Manning/ORNL, U.S. Dept. of Energy

Quantum Network Achieves 100% Uptime on Commercial Fiber System

Scientists at Oak Ridge National Laboratory successfully transmitted entangled quantum signals without interruption over a commercial fiber-optic network using automatic polarization compensation, marking a crucial advance toward practical quantum internet development.

Professor Johannes Fink at the Institute of Science and Technology Austria (ISTA): A team of physicists from his group achieved a fully optical readout of superconducting qubits. Credit: © Nadine Poncioni | ISTA

Fiber Optics: The Missing Link in Quantum Computing’s Future

ISTA physicists have developed a breakthrough method to connect superconducting qubits using fiber optics instead of traditional electrical signals, significantly reducing cooling requirements and potentially enabling the scaling and networking of quantum computers by converting optical signals to microwave frequencies that qubits can process.

Proposed scheme for two-dimensional states generation.

MacZac: A High-Stability Time-Bin Encoder for Quantum Key Distribution

A novel quantum key distribution encoder called MacZac combines Sagnac and Mach-Zehnder interferometers with a single phase modulator to achieve exceptionally low error rates and high stability in time-bin encoded quantum communications, while simplifying the optical setup and eliminating the need for active compensation.

Protocol scheme with arbitrary modes.

High-dimensional coherent one-way Quantum Key Distribution (QKD)

Scientists have introduced and analyzed a high-dimensional QKD protocol that requires only standard two-dimensional hardware. They have provided security analysis against individual and coherent attacks, establishing upper and lower bounds on the secure key rates.

Northwestern University logo

Quantum Network Breakthrough: Less is More in Maintaining Quantum Links

Northwestern University researchers discovered that quantum networks can be maintained by adding just the square root number of new connections relative to total users after each communication event, offering a surprisingly efficient solution to the challenge of quantum links disappearing once used.

Professor Liang Feng and group members Xilin Feng, Tianwei Wu, and Shuang Wu, from left. Credit: Bella Ciervo

Quantum Physics Powers New Era of Ultra-Fast Optical Switches

Researchers at the University of Pennsylvania’s School of Engineering and Applied Science have developed a revolutionary photonic switch that transforms data transmission in fiber-optic networks. The switch, detailed in Nature Photonics, measures just 85 by […]

Schematic of the experimental setup including a spectrally-multiplexed photon pair source, a VIPA-based demultiplexer for mapping spectral modes to distinct spatial channels, and a Tm3+:LiNbO3-based spectral filter: APD - avalanche photodiode; DDG - digital delay generator; SNSPD - superconducting nanowire single photon detector; AD - achromatic Doublet (focusing lens coupling the output beam into collection fiber).

Towards a spectrally multiplexed quantum repeater

Extended quantum networks are based on quantum repeaters that often rely on the distribution of entanglement in an efficient and heralded fashion over multiple network nodes. Many repeater architectures require multiplexed sources of entangled photon […]

Roberto Morandotti. Credits : Josée Lecompte

Quantum research breakthrough uses synthetic dimensions to efficiently process quantum information

A new study opens the door to cutting-edge solutions that could contribute to the realization of a system capable of processing quantum information in a simple yet powerful way. The work presents a method for manipulating the photonic states of light in a never-before-seen way, offering greater control over the evolution of photon propagation. This control makes it possible to improve the detection and number of photon coincidences, as well as the efficiency of the system.