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We present a quantum key distribution (QKD) system based on polarisation entanglement for use in telecom fibers. A QKD exchange up to 50km was demonstrated in the laboratory with a secure key rate of 550 bit/s. The system is compact,…

Quantum cryptography allows confidential information to be communicated between two parties, with secrecy guaranteed by the laws of nature alone. However, upholding guaranteed secrecy over quantum communication networks poses a further…

We demonstrate non-degenerate down-conversion at 810 and 1550 nm for long-distance fiber based quantum communication using polarization entangled photon pairs. Measurements of the two-photon visibility, without dark count subtraction, have…

We use a small atomic Bose-Einstein condensate as an interferometric scanning probe to map out a microwave field near a chip surface with a few micrometers resolution. Using entanglement between the atoms we overcome the standard quantum…

Quantum Physics · Physics 2013-10-30 Caspar F. Ockeloen , Roman Schmied , Max F. Riedel , Philipp Treutlein

Measurement-device-independent quantum key distribution (MDI-QKD) removes all detector side channels and enables secure QKD with an untrusted relay. It is suitable for building a star-type quantum access network, where the complicated and…

Quantum cryptographic key distribution (QKD) uses extremely faint light pulses to carry quantum information between two parties (Alice and Bob), allowing them to generate a shared, secret cryptographic key. Autocompensating QKD systems…

Quantum Physics · Physics 2009-11-07 Donald S. Bethune , William P. Risk

Some guidelines for the comparison of different quantum key distribution experiments are proposed. An improved 'plug & play' interferometric system allowing fast key exchange is then introduced. Self-alignment and compensation of…

Quantum Physics · Physics 2015-06-26 Gregoire Ribordy , Jean-Daniel Gautier , Nicolas Gisin , Olivier Guinnard , Hugo Zbinden

Security in quantum cryptography is continuously challenged by inventive attacks targeting the real components of a cryptographic setup, and duly restored by new counter-measures to foil them. Due to their high sensitivity and complex…

A quantum key distribution system has been developed, using standard telecommunications optical fiber, which is capable of operating at clock rates of greater than 1 GHz. The quantum key distribution system implements a polarization encoded…

Quantum Physics · Physics 2007-05-23 Karen J. Gordon , Veronica Fernandez , Paul D. Townsend , Gerald S. Buller

We propose an auto-compensating differential phase shift scheme for quantum key distribution with a high key-creation efficiency, which skillfully makes use of automatic alignment of the photon polarization states in optical fiber with…

Quantum Physics · Physics 2007-05-23 Xiaohong Han , Guang Wu , Chunyuan Zhou , Heping Zeng

We demonstrate single-photon interference over 100 km using a balanced gated-mode photon detector and a plug & play system for quantum key distribution. The visibility with 0.1 photon/pulse was more than 80% after 100 km transmission. This…

Quantum Physics · Physics 2007-05-23 Hideo Kosaka , Akihisa Tomita , Yoshihiro Nambu , Tadamasa Kimura , Kazuo Nakamura

Standard quantum key distribution (QKD) protocols typically assume that the distant parties share a common reference frame. In practice, however, establishing and maintaining a good alignment between distant observers is rarely a trivial…

Quantum Physics · Physics 2014-04-04 Joshua A. Slater , Cyril Branciard , Nicolas Brunner , Wolfgang Tittel

Optical quantum nondemolition devices can provide essential tools for quantum information processing. Here, we describe several optical interferometers that signal the presence of a single photon in a particular input state without…

Quantum Physics · Physics 2009-11-07 Pieter Kok , Hwang Lee , Jonathan P. Dowling

Intermodal quantum key distribution at telecom wavelengths provides a hybrid interface between fiber connections and free-space links, both essential for the realization of scalable and interoperable quantum networks. Although demonstrated…

We present and demonstrate a new protocol for practical quantum cryptography, tailored for an implementation with weak coherent pulses to obtain a high key generation rate. The key is obtained by a simple time-of-arrival measurement on the…

Quantum Physics · Physics 2009-11-11 Damien Stucki , Nicolas Brunner , Nicolas Gisin , Valerio Scarani , Hugo Zbinden

Quantum mechanics allows the distribution of intrinsically secure encryption keys by optical means. Twin-field quantum key distribution is the most promising technique for its implementation on long-distance fibers, but requires stabilizing…

We have experimentally realized a technique to generate, control and measure entangled qutrits, 3-dimensional quantum systems. This scheme uses spontaneous parametric down converted photons and unbalanced 3-arm fiber optic interferometers…

Quantum Physics · Physics 2007-05-23 R. T. Thew , A. Acin , H. Zbinden , N. Gisin

Measurement-device-independent quantum key distribution (MDI-QKD) can eliminate all detector side channels and it is practical with current technology. Previous implementations of MDI-QKD all use two symmetric channels with similar losses.…

While measurement-device-independent (MDI) quantum key distribution (QKD) allows two trusted parties to establish a shared secret key from a distance without needing to trust a central detection node, their quantum sources must be…

Quantum Physics · Physics 2023-01-04 J. Eli Bourassa , Amita Gnanapandithan , Li Qian , Hoi-Kwong Lo

We report a demonstration of quantum key distribution (QKD) over a standard telecom fiber exceeding 50 dB in loss and 250 km in length. The differential phase shift QKD protocol was chosen and implemented with 2 GHz system clock rate. By…

Quantum Physics · Physics 2012-03-21 Shuang Wang , Wei Chen , Jun-Fu Guo , Zhen-Qiang Yin , Hong-Wei Li , Zheng Zhou , Guang-Can Guo , Zheng-Fu Han