Quantum Information Processing

Su, Qi; Li, Wen-Min

2014 Quantum Information Processing

doi: 10.1007/s11128-014-0778-y

A digital signature is a mathematical scheme for demonstrating the authenticity of a digital message or document. A blind signature is a form of digital signature in which the content of a message is disguised (blinded) before it is signed to protect the privacy of the message from the signatory. For signing quantum messages, some quantum blind signature protocols have been proposed. Recently, Khodambashi et al. (Quantum Inf Process 13:121, 2014) proposed a sessional blind signature based on quantum cryptography. It was claimed that these protocol could guarantee unconditional security. However, after our analysis, we find that the signature protocol will cause the key information leakage in the view of information theory. Taking advantage of loophole, the message sender can succeed in forging the signature without the knowledge of the whole exact key between the verifier and him. To conquer this shortcoming, we construct an improved protocol based on it and the new protocol can resist the key information leakage attacks.

Yang, Yu-Guang; Xu, Peng; Tian, Ju; Zhang, Hua

2014 Quantum Information Processing

doi: 10.1007/s11128-014-0783-1

We investigate the dynamic watermarking scheme for quantum images using quantum wavelet transform (QWT) proposed by Song et al. (Quantum Inf Process 12(12):3689–3706, 2013). It is aimed to embed the watermark image into the wavelet coefficients of the quantum carrier image. However, in our opinion, the key procedures of the protocol are wrong. At last, a possible improvement strategy is presented.

Abdel-Aty, M.; Bouchene, M.; McGurn, A.

2014 Quantum Information Processing

doi: 10.1007/s11128-014-0787-x

We consider a multi-qubit system consisting of two trapped ions coupled in a laser field. The ions are identical three-level electronic systems which interact with one another through the phonon modes of their relative or center of mass motions, and the system is tuned so that two-phonon processes dominate the electronic transitions. The resulting evolution of the system is studied theoretically with a focus on the entanglement properties of the system. A method of quantifying the entanglement is discussed, and the time dependence of these quantifications is determined. The cases of the two ions coupled to the same phonon field and to two different isolated phonon fields are compared for Fock cavity modes. Instances of the entanglement sudden death recovery are identified in these various systems.

Ma, Song-Ya; Luo, Ming-Xing; Chen, Xiu-Bo; Yang, Yi-Xian

2014 Quantum Information Processing

doi: 10.1007/s11128-014-0788-9

Two schemes via different entangled resources as the quantum channel are proposed to realize remote preparation of an arbitrary four-particle $$\chi $$ χ -state with high success probabilities. To design these protocols, some useful and general measurement bases are constructed, which have no restrictions on the coefficients of the prepared states. It is shown that through a four-particle projective measurement and two-step three-particle projective measurement under the novel sets of mutually orthogonal basis vectors, the original state can be prepared with the probability 50 and 100 %, respectively. And for the first scheme, the special cases of the prepared state that the success probability reaches up to 100 % are discussed by the permutation group. Furthermore, the present schemes are extended to the non-maximally entangled quantum channel, and the classical communication costs are calculated.

Fan, Lin-Lin; Xia, Yan; Song, Jie

2014 Quantum Information Processing

doi: 10.1007/s11128-014-0789-8

We present an efficient protocol to concentrate arbitrary less-hyperentangled multi-photon W states to the maximally hyperentangled multi-photon W state with parameter-splitting method and linear optics elements. Compared with previous entanglement concentration works, the present protocol does not need two copies of partially entangled states or the ancillary single photon. Moreover, we discuss the feasibility of the setups of the protocol, concluding that the present protocol is feasible with the current technology. Thus, the protocol may be more meaningful in practical quantum information applications.

Zhang, Zhi-Hua; Shu, Lan; Mo, Zhi-Wen; Zheng, Jun; Ma, Song-Ya; Luo, Ming-Xing

2014 Quantum Information Processing

doi: 10.1007/s11128-014-0790-2

In this work, novel schemes for joint remote state preparation are presented, which involve N senders and 2 receivers as well as N senders and 3 receivers. The receivers can simultaneously reconstruct different qubit states containing the joint information from all senders. Compared with the protocols proposed by Su et al. (Int J Quantum Inf 10:1250006 (2012), the information of the prepared states in our schemes is distributed in a different way. Our protocols can be applied not only to states with real parameters but also ones with complex parameters. Moreover, the N-to-2 protocol is suitable for general qubit states besides equatorial states, and the receivers need not to perform any measurements and CNOT gates to reconstruct the states.

Yang, Chun-Wei; Luo, Yi-Ping; Hwang, Tzonelih

2014 Quantum Information Processing

doi: 10.1007/s11128-014-0795-x

This paper points out that in Wang and Wei’s scheme (Quantum Inf Process 11:455–463, 2012), an eavesdropper, Eve, can replace the original message of a proxy signature with a forged one of her choice without being detected by the verifier. Accordingly, one of the security requirements of a quantum signature, i.e., unforgeability, may not be satisfied in their scheme. An improvement is given to avoid this attack, and the comparisons with the existing quantum proxy signature are also demonstrated.

Sharma, Kapil; Pandey, S.

2014 Quantum Information Processing

doi: 10.1007/s11128-014-0794-y

We study entanglement dynamics in two-parameter qubit–qutrit states under the influence of Dzyaloshisnhkii–Moriya (DM) interaction. Our system consists of a qubit–qutrit pair as a closed system initially in two-parameter class of states, and one environmental qubit interacts with the qutrit of the closed system via DM interaction. We divide our analysis into two cases. In the first case, we study the entanglement dynamics in separable region, and in the second case we study the same in non-separable region. The DM interaction produces the entanglement in separable region with entanglement sudden death (ESD) and some states in this region remain unaffected by the same. In non-separable region, all the states are affected by DM interaction. The DM interaction excites the entanglement but does not produce ESD in this region. We observed that probability amplitude of environmental qubit does not affect the entanglement in two-parameter qubit–qutrit states in both the regions.

Guo, Ying; Zhao, Zhisheng; Wang, Yijun; Wang, Ping; Huang, Dazu; Lee, Moon

2014 Quantum Information Processing

doi: 10.1007/s11128-014-0798-7

We investigate an novel implementation of a Toffoli gate using multiple independent auxiliary photons prepared beforehand in single-qubit states. This gate can be performed nondestructively with entanglement swapping via the Greenberger–Horne–Zeilinger state analysis. We evaluate the performance of the proposed Toffoli gate with the fidelity based on different computation bases. The multi-qubit-entanglement gate is no longer theoretical since it can be implemented in principle with single-qubit photons.

Chakraborty, Kaushik; Choi, Byung-Soo; Maitra, Arpita; Maitra, Subhamoy

2014 Quantum Information Processing

doi: 10.1007/s11128-014-0797-8

In this paper, we study several quantum algorithms toward the efficient construction of arbitrary arbitrary Dicke state. The proposed algorithms use proper symmetric Boolean functions that involve manipulation with Krawtchouk polynomials. Deutsch–Jozsa algorithm, Grover algorithm, and the parity measurement technique are stitched together to devise the complete algorithm. In addition to that we explore how the biased Hadamard transformation can be utilized into our strategy, motivated by the work of Childs et al. (Quantum Inf Comput 2(3):181–191, 2002).