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We study distribution schemes for a polarization entangled photon pair based on a decoherence-free subspace over lossy quantum channels and propose an efficient scheme that is robust against not only collective phase noises but also general…

Quantum Physics · Physics 2013-06-17 Hidetoshi Kumagai , Takashi Yamamoto , Masato Koashi , Nobuyuki Imoto

Single photons are the flying qubits of choice for distributing entanglement in a quantum internet. Quantum memories embedded in quantum repeaters are crucial to overcome transmission loss and enhance the rate of quantum communication. A…

Quantum Physics · Physics 2026-03-03 H. -X Luo , C. Li , J. -L. Ren , Y. Yuan , Y. -L. Wen , J. -F. Li , Y. -F. Wang , S. -C. Zhang , H. Yan , S. -L. Zhu

Quantum teleportation enables the deterministic exchange of qubits via lossy channels. While it is commonly believed that unconditional teleportation requires a preshared entangled qubit pair, here we demonstrate a protocol that is in…

Photonic polarization qubits are widely used in quantum computation and quantum communication due to the robustness in transmission and the easy qubit manipulation. An integrated quantum memory for polarization qubits is a fundamental…

The transfer of data is a fundamental task in information systems. Microprocessors contain dedicated data buses that transmit bits across different locations and implement sophisticated routing protocols. Transferring quantum information…

A quantum memory, for storing and retrieving flying photonic quantum states, is a key interface for realizing long-distance quantum communication and large-scale quantum computation. While many experimental schemes of high storage-retrieval…

Quantum Physics · Physics 2020-04-15 Y. Wang , J. Li , S. Zhang , K. Su , Y. Zhou , K. Liao , S. Du , H. Yan , S. L. Zhu

To implement the BB84 decoy-state quantum key distribution (QKD) protocol over a lossy ground-satellite quantum uplink requires a source that has high repetition rate of short laser pulses, long term stability, and no phase correlations…

Random generation and confidential distribution of cryptographic keys are fundamental building blocks of secure communication. Using quantum states in which the transmitted quantum bit is entangled with a stationary memory quantum bit…

Quantum Physics · Physics 2021-11-30 Pascal Kobel , Ralf A. Berner , Michael Köhl

Quantum key distribution relies on quantum mechanics to securely distribute cryptographic keys, offering security but necessitating complex infrastructure and significant resources for practical implementation. Quantum keyless private…

Quantum Physics · Physics 2026-03-02 Pedro Neto Mendes , Davide Rusca , Hugo Zbinden , Emmanuel Zambrini Cruzeiro

Quantum memories are essential components of quantum networks, enabling synchronization, quantum repeaters, and long-distance entanglement distribution. Most ensemble-based realizations rely on dark-state polaritons (DSPs) in $\Lambda$-type…

Quantum Physics · Physics 2025-10-14 Dounan Du , Eden Figueroa

We present an experimental method to detect lower bounds to the quantum capacity of two-qubit communication channels. We consider an implementation with polarisation degrees of freedom of two photons and report on the efficiency of such a…

In this paper, we show that quantum memory for qudit states encoded in a single photon pulsed optical field has a conceptually simple modular realization using only passive linear optics and coherent feedback. We exploit the idea that two…

Quantum Physics · Physics 2015-08-03 Hendra I. Nurdin , John E. Gough

In quantum teleportation, the state of a single quantum system is disembodied into classical information and purely quantum correlations, to be later reconstructed onto a second system that has never directly interacted with the first one.…

Quantum communication provides an absolute security advantage, and it has been widely developed over the past 30 years. As an important branch of quantum communication, quantum secure direct communication (QSDC) promotes high security and…

Quantum Physics · Physics 2017-06-07 Wei Zhang , Dong-Sheng Ding , Yu-Bo Sheng , Lan Zhou , Bao-Sen Shi , Guang-Can Guo

We report on a complete experimental implementation of a quantum key distribution protocol through a free space link using polarization-entangled photon pairs from a compact parametric down-conversion source. Over 10 hours of uninterrupted…

Quantum Physics · Physics 2007-05-23 Ivan Marcikic , Antia Lamas-Linares , Christian Kurtsiefer

We show that the problem of communication in a quantum computer reduces to constructing reliable quantum channels by distributing high-fidelity EPR pairs. We develop analytical models of the latency, bandwidth, error rate and resource…

Quantum Physics · Physics 2007-05-23 Nemanja Isailovic , Yatish Patel , Mark Whitney , John Kubiatowicz

The big challenge in quantum computing is to realize scalable multi-qubit systems with cross-talk free addressability and efficient coupling of arbitrarily selected qubits. Quantum networks promise a solution by integrating smaller qubit…

Light is an irreplaceable means of communication among various quantum information processing and storage devices. Due to their different physical nature, some of these devices couple more strongly to discrete, and some to continuous…

Various near-term quantum networking applications will benefit from low-loss, fiber-coupled photonic quantum memory devices with high efficiencies. We demonstrate a fiber-coupled loop-and-switch quantum memory platform with a pass-through…

Quantum Physics · Physics 2025-10-23 Sandra Cheng , Carson Evans , Todd Pittman

We derive the general structure of noiseless subsystems for optical radiation contained in a sequence of pulses undergoing collective depolarization in an optical fiber. This result is used to identify optimal ways to implement quantum…

Quantum Physics · Physics 2016-09-08 Jonathan L. Ball , Konrad Banaszek