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We present two efficient quantum key distribution schemes over two different collective-noise channels. The accepted hypothesis of collective noise is that photons travel inside a time window small compared to the variation of noise.…

Quantum Physics · Physics 2009-11-13 Xi-Han Li , Fu-Guo Deng , Hong-Yu Zhou

We consider the asymptotic key rates achieved in the simplest quantum key distribution protocols, namely the BB84 and the six-state protocols, when non-uniform noise is present in the system. We first observe that higher qubit error rates…

Quantum Physics · Physics 2020-07-02 Gláucia Murta , Filip Rozpędek , Jérémy Ribeiro , David Elkouss , Stephanie Wehner

A scheme to implement a quantum computer subjected to decoherence and governed by an untunable qubit-qubit interaction is presented. By concatenating dynamical decoupling through bang-bang (BB) pulse with decoherence-free subspaces (DFSs)…

Quantum Physics · Physics 2007-05-23 Yong Zhang , Zheng-Wei Zhou , Bo Yu , Guang-Can Guo

We analyze robustness of decoherence-free (DF) subspace in charge qubits when there are a local structure and non-uniformity that violate collective decoherence measurement condition. We solve master equations of up to four charge qubits…

Quantum Physics · Physics 2014-01-08 Tetsufumi Tanamoto , Shinobu Fujita

We introduce a novel form of decoy-state technique to make the single-photon Bennett 1992 protocol robust against losses and noise of a communication channel. Two uninformative states are prepared by the transmitter in order to prevent the…

Quantum Physics · Physics 2009-09-25 Marco Lucamarini , Giovanni Di Giuseppe , Kiyoshi Tamaki

We analyze decoherence-free (DF) quantum information in the presence of an arbitrary non-nearest-neighbor bath-induced system Hamiltonian using a Markovian master equation. We show that the most appropriate encoding for N qubits is probably…

Quantum Physics · Physics 2008-06-25 Peter G. Brooke , James D. Cresser , Manas K. Patra

Mutually unbiased bases determine an optimal set of measurements to extract complete information about the quantum state of a system. However, quite often a priori information about the state exist, making some of the measurement bases…

Quantum Physics · Physics 2015-06-12 A. B. Klimov , G. Bjork , L. L. Sanchez-Soto

It was shown recently [D.A. Lidar et al., Phys. Rev. Lett. 81, 2594 (1998)] that within the framework of the semigroup Markovian master equation, decoherence-free (DF) subspaces exist which are stable to first order in time to a…

Quantum Physics · Physics 2009-10-31 D. Bacon , D. A. Lidar , K. B. Whaley

The construction of large, coherent quantum systems necessary for quantum computation remains an entreating but elusive goal, due to the ubiquitous nature of decoherence. Recent progress in quantum error correction schemes have given new…

Quantum Physics · Physics 2008-02-03 Isaac L. Chuang , Yoshihisa Yamamoto

Quantum key distribution (QKD) based on coherent states is well known for its implementation simplicity, but it suffers from loss-dependent attacks based on optimal unambiguous state discrimination. Crucially, previous research has…

Quantum Physics · Physics 2020-06-05 Li Liu , Yukun Wang , Emilien Lavie , Arno Ricou , Chao Wang , Fen Zhuo Guo , Charles Ci Wen Lim

We attempt to propose the first orthogonal-state-based protocols of measurement-device-independent quantum secure direct communication and quantum dialogue employing single basis, i.e., Bell basis as decoy qubits for eavesdropping…

Quantum Physics · Physics 2024-10-01 Chitra Shukla , Abhishek Shukla , Symeon Chatzinotas , Milos Nesladek

We consider the security of the Bennett-Brassard 1984 (BB84) protocol for Quantum Key Distribution (QKD), in the presence of bit and basis dependent detector flaws. We suggest a powerful attack that can be used in systems with detector…

Quantum Physics · Physics 2010-01-04 L. Lydersen , J. Skaar

The random switching of measurement bases is commonly assumed to be a necessary step of quantum key distribution protocols. In this paper we show that switching is not required for coherent state continuous variable quantum key…

In majority of protocols of secure quantum communication (such as, BB84, B92, etc.), the unconditional security of the protocols are obtained by using conjugate coding (two or more mutually unbiased bases). Initially all the…

Quantum Physics · Physics 2022-06-07 Chitra Shukla , Anindita Banerjee , Anirban Pathak , R. Srikanth

Quantum key distribution (QKD) offers a theoretically secure method to share secret keys, yet practical implementations face challenges due to noise and loss over long-distance channels. Traditional QKD protocols require extensive noise…

Quantum Physics · Physics 2025-08-01 Hannah Seabrook , Emilien Lavie , Teodor Strömberg , Matthew P. Stafford , Giulia Rubino

Universal quantum computation on decoherence-free subspaces and subsystems (DFSs) is examined with particular emphasis on using only physically relevant interactions. A necessary and sufficient condition for the existence of…

Quantum Physics · Physics 2009-11-06 Julia Kempe , Dave Bacon , Daniel A. Lidar , K. Birgitta Whaley

Reference-frame-independent quantum key distribution (RFI QKD) protocol can reduce the requirement on the alignment of reference frames in practical systems. However, comparing with the Bennett-Brassard (BB84) QKD protocol, the main…

Quantum Physics · Physics 2019-09-25 Hongwei Liu , Jipeng Wang , Haiqiang Ma , Shihai Sun

In idealized models of a quantum register and its environment, quantum information can be stored indefinitely by encoding it into a decoherence-free subspace (DFS). Nevertheless, perturbations to the idealized register-environment coupling…

Quantum Physics · Physics 2019-07-03 Joris Kattemölle , Jasper van Wezel

This note presents a method of public key distribution using quantum communication of n photons that simultaneously provides a high probability that the bits have not been tampered. It is a three-state variant of the quantum method of…

Quantum Physics · Physics 2009-06-19 Subhash Kak

Characterizing a quantum process is the critical first step towards applying such a process in a quantum information protocol. Full process characterization is known to be extremely resource-intensive, motivating the search for more…

Quantum Physics · Physics 2015-06-05 D. H. Mahler , L. Rozema , A. Darabi , A. M. Steinberg