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High-dimensional entanglement is a valuable resource for quantum communication, and photon pairs entangled in orbital angular momentum are commonly used for encoding high-dimensional quantum states. However, methods for preparation of…

Quantum Physics · Physics 2018-12-19 Egor Kovlakov , Stanislav Straupe , Sergey Kulik

Spatial states of single photons and spatially entangled photon pairs are becoming an important resource in quantum communication. This additional degree of freedom provides an almost unlimited information capacity, making the development…

Quantum Physics · Physics 2017-01-26 E. V. Kovlakov , I. B. Bobrov , S. S. Straupe , S. P. Kulik

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 propose a scheme for long-distance quantum communication where the elementary entanglement is generated through two-photon interference and quantum swapping is performed through one-photon interference. Local "polarization" maximally…

Quantum Physics · Physics 2010-03-03 Fang-Yu Hong , Shi-Jie Xiong , W. H. Tang

We introduce protocols for designing and manipulating qubits with ultracold alkali atoms in 3D optical lattices. These qubits are formed from two-atom spin superposition states that create a decoherence-free subspace immune to stray…

Quantum Physics · Physics 2023-05-23 Mikhail Mamaev , Joseph H. Thywissen , Ana Maria Rey

A significant obstacle for practical quantum computation is the loss of physical qubits in quantum computers, a decoherence mechanism most notably in optical systems. Here we experimentally demonstrate, both in the quantum circuit model and…

Quantum Physics · Physics 2016-05-16 Chao-Yang Lu , Wei-Bo Gao , Jin Zhang , Xiao-Qi Zhou , Tao Yang , Jian-Wei Pan

We report on theoretical and experimental demonstration of high-efficiency coupling of two-photon entangled states produced in the nonlinear process of spontaneous parametric down conversion into a single-mode fiber. We determine…

Quantum Physics · Physics 2015-06-26 F. A. Bovino , P. Varisco , A. M. Colla , G. Castagnoli , G. Di Giuseppe , A. V. Sergienko

Hybrid encodings, where multiple degrees of freedom are used to encode quantum information, can increase the size of the Hilbert space with minimal increase to hardware requirements. We show a reprogrammable integrated photonic device, with…

We observe polarization-entanglement between four photons produced from a single down-conversion source. The non-classical correlations between the measurement results violate a generalized Bell inequality for four qubits. The…

Quantum Physics · Physics 2009-11-10 M. Eibl , S. Gaertner , M. Bourennane , Ch. Kurtsiefer , M. Zukowski , H. Weinfurter

Two schemes for sharing an arbitrary two-qubit state based on entanglement swapping are proposed with Bell-state measurements and local unitary operations. One is based on the quantum channel with four Einstein-Podolsky-Rosen (EPR) pairs…

Quantum Physics · Physics 2009-11-11 Fu-Guo Deng , Xi-Han Li , Chun-Yan Li , Ping Zhou , Hong-Yu Zhou

Quantum cryptography and quantum key distribution (QKD) have been the most successful applications of quantum information processing, highlighting the unique capability of quantum mechanics, through the no-cloning theorem, to protect the…

Quantum Physics · Physics 2012-06-18 David S. Simon , Nate Lawrence , Jacob Trevino , Luca Dal Negro , Alexander V. Sergienko

Polarization-encoded free-space Quantum Communication requires a quantum state source featuring fast polarization modulation, long-term stability and a low intrinsic error rate. Here we present a source based on a Sagnac interferometer and…

Quantum Physics · Physics 2020-08-27 Marco Avesani , Costantino Agnesi , Andrea Stanco , Giuseppe Vallone , Paolo Villoresi

We present a linear optical scheme for error-free distribution of two-photon polarization entangled Bell states over noisy channels. The scheme can be applied to an elementary quantum repeater protocol with potentially significant…

Quantum Physics · Physics 2009-11-13 Demetrios Kalamidas

Distributing entangled states over potentially long distances provides a key resource for many protocols in quantum communication and quantum cryptography. Ideally, this should be implemented in a heralded manner. By starting with four…

Quantum Physics · Physics 2024-06-19 Francis Marcellino , Patrik Caspar , Tiff Brydges , Hugo Zbinden , Rob Thew

Quantum information contained in single-particle states can be masked by mapping them to entangled states. In this paper, we consider entanglement swapping under the masking of quantum information. Our work can pave the way for developing…

Quantum Physics · Physics 2021-11-17 Zhaoxu Ji , Peiru Fan , Atta Ur Rahman , Huanguo Zhang

Controlling and engineering continuous spectral modes of entangled photons represents one of the promising approaches toward secure quantum communications. By using the telecom bandwidth generated from a cascade-emitted biphoton in atomic…

Quantum Physics · Physics 2023-12-15 N. -Y Tsai , H. H. Jen

Fiber transport of multi-dimensional photonic qudits promises high information capacity per photon without space restriction. This work experimentally demonstrates transmission of spatial qudits through multi-core optical fibers and…

Quantum Physics · Physics 2016-10-17 Hee Jung Lee , Sang-Kyung Choi , Hee Su Park

Transfer of quantum information between physical systems of a different nature is a central matter in quantum technologies. Particularly challenging is the transfer between discrete- and continuous degrees of freedom of various harmonic…

In this paper we propose a technique for distributing entanglement in architectures in which interactions between pairs of qubits are constrained to a fixed network $G$. This allows for two-qubit operations to be performed between qubits…

Quantum Physics · Physics 2020-11-04 Niel de Beaudrap , Steven Herbert

We expand on our work on Quantum Data Hiding -- hiding classical data among parties who are restricted to performing only local quantum operations and classical communication (LOCC). We review our scheme that hides one bit between two…

Quantum Physics · Physics 2016-11-18 David P. DiVincenzo , Debbie W. Leung , Barbara M. Terhal