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We propose a cryptographic scheme that is deterministic: Alice sends single photons to Bob, and each and every photon detected supplies one key bit -- no photon is wasted. This is in marked contrast to other schemes in which a random…

Quantum Physics · Physics 2009-11-07 Almut Beige , Berthold-Georg Englert , Christian Kurtsiefer , Harald Weinfurter

We present a scheme to realize a quantum key distribution using vacuum-one photon entangled states created both from Alice and Bob. The protocol consists in an exchange of spatial modes between Alice and Bob and in a recombination which…

Quantum Physics · Physics 2007-05-23 Gian Luca Giorgi

This paper summarizes our recent progress towards using single rubidium atoms trapped in an optical tweezer to encode quantum information. We demonstrate single qubit rotations on this system and measure the coherence of the qubit. We move…

The probabilistic nature of single-photon sources and photon-photon interactions encourages encoding as much quantum information as possible in every photon for the purpose of photonic quantum information processing. Here, by encoding…

We propose a scheme of quantum secret sharing between Alices' group and Bobs' group with single photons and unitary transformations. In the protocol, one member in Alices' group prepares a sequence of single photons in one of four different…

Quantum Physics · Physics 2009-11-13 Feng-Li Yan , Ting Gao , You-Cheng Li

We propose a quantum measurement that probabilistically projects a pair of qudits of dimension $d$ onto a Bell state in a two-qubit subspace. It can be performed using linear-optical circuits with the success probabilities of $1-d^{-1}$…

Quantum Physics · Physics 2025-10-23 Tomohiro Yamazaki , Koji Azuma

We consider a situation in which two parties, Alice and Bob, share a 3-qubit system coupled in an initial maximally entangled, GHZ state. By manipulating locally two of the qubits, Alice can prepare any one of the eight 3-qubit GHZ states.…

Quantum Physics · Physics 2007-05-23 Jose L. Cereceda

When photons are sent through a fiber as part of a quantum communication protocol, the error that is most difficult to correct is photon loss. Here, we propose and analyze a two-to-four qubit encoding scheme, which can recover the loss of…

Quantum Physics · Physics 2009-11-10 Robert M. Gingrich , Pieter Kok , Hwang Lee , Farrokh Vatan , Jonathan P. Dowling

In this paper, we report on experimental implementation of a linear-optical quantum router. Our device allows single-photon polarization-encoded qubits to be routed coherently into two spatial output modes depending on the state of two…

Quantum Physics · Physics 2018-09-12 Karol Bartkiewicz , Antonín Černoch , Karel Lemr

We present the experimental realization of optimal symmetric and asymmetric phase-covariant 1->2 cloning of qubit states using fiber optics. State of each qubit is encoded into a single photon which can propagate through two optical fibers.…

Quantum Physics · Physics 2009-11-13 Lucie Bartuskova , Miloslav Dusek , Antonin Cernoch , Jan Soubusta , Jaromir Fiurasek

The best qubit one-way quantum key distribution (QKD) protocol can tolerate up to 14.1% in the error rate. It has been shown how this rate can be increased by using larger quantum systems. The polarization state of a biphoton can encode a…

Quantum Physics · Physics 2009-11-13 I. Bregman , D. Aharonov , M. Ben-Or , H. S. Eisenberg

We study the mapping which occurs when a single qubit in an arbitrary state interacts with another qubit in a given, fixed state resulting in some unitary transformation on the two qubit system which, in effect, makes two copies of the…

Quantum Physics · Physics 2009-10-31 Chi-Sheng Niu , Robert B. Griffiths

In this paper, a novel protocol is proposed for implementing BQCT by using five-qubit en The proposed protocol depends on the Controlled-NOT operation, proper single-qubit unitary operations and single-qubit measurement in the Z-basis and…

Quantum Physics · Physics 2018-06-20 Moein Sarvaghad-Moghaddam , Ahmed Farouk , Hussein Abulkasim

We introduce a general mapping for encoding quantum communication protocols involving pure states of multiple qubits, unitary transformations, and projective measurements into another set of protocols that employ coherent states of light in…

Quantum Physics · Physics 2014-11-05 Juan Miguel Arrazola , Norbert Lütkenhaus

We put forward an effective amplification protocol for protecting the single-photon entangled state of the time-bin qubit. The protocol only requires one pair of the single-photon entangled state and some auxiliary single photons. With the…

Quantum Physics · Physics 2016-06-01 Lan Zhou , Yu-Bo Sheng

We demonstrate the possibility to perform distributed quantum computing using only single photon sources (atom-cavity-like systems), linear optics and photon detectors. The qubits are encoded in stable ground states of the sources. To…

Quantum Physics · Physics 2009-11-10 Yuan Liang Lim , Almut Beige , Leong Chuan Kwek

We propose a novel scheme to implement the BB84 quantum key distribution (QKD) protocol in optical fibers based on a quantum frequency-translation (QFT) process. Unlike conventional QKD systems, which rely on photon polarization/phase to…

Quantum Physics · Physics 2018-07-02 J. Bonetti , S. M. Hernandez , D. F. Grosz

We describe a protocol capable of preparing an arbitrary state of two photons in several spatial modes using pairs of photons generated by spontaneous parametric down-conversion, linear optical elements and single-photon detectors or…

Quantum Physics · Physics 2009-11-13 Karel Lemr , Jaromir Fiurasek

We propose a protocol that allows both the creation and distribution of entanglement, resulting in two distant parties (Alice and Bob) conclusively sharing a bipartite Bell State. The system considered is a graph of three-level objects…

Quantum Physics · Physics 2007-05-23 Christopher Hadley , Alessio Serafini , Sougato Bose

We develop a quantum teleportation protocol of an unknown optical single rail qubit using a hybrid quantum channel composed of continuous variable (CV) states of certain parity. The quantum channel is characterized by two parameters: a…

Quantum Physics · Physics 2026-03-12 Mikhail S. Podoshvedov , Sergey A. Podoshvedov