|
Books
Next| 2009-06-04T04:02:35Z | | Hierarchical quantum information splitting | | We present a scheme for asymmetric quantum information splitting, where a
sender distributes asymmetrically a qubit to distant agents in a network. The
asymmetric distribution leads to that the agents have different powers to
reconstruct the sender's qubit. In other words, the authorities of the agents
for getting the quantum secret are hierarchized. The scheme does not need the
agents to get together and make nonlocal operations. Our scheme can also be
modified to implement controlled teleportation against uncooperation of part of
supervisors.
| |
| 2011-01-19T14:48:03Z | | Multiparty hierarchical quantum-information splitting | | We propose a scheme for multiparty hierarchical quantum-information splitting
(QIS) with a multipartite entangled state, where a boss distributes a secret
quantum state to two grades of agents asymmetrically. The agents who belong to
different grades have different authorities for recovering boss's secret.
Except for boss's Bell-state measurement, no nonlocal operation is involved.
The presented scheme is also shown to be secure against eavesdropping. Such a
hierarchical QIS is expected to find useful applications in the field of modern
multipartite quantum cryptography.
| |
| 2011-09-25T07:50:54Z | | Optimal ancilla-free phase-covariant telecloning of qudits via
nonmaximally entangled states | | We study the one-to-two phase-covariant telecloning of a qudit without
ancilla. We show that the fidelity of the two clones can reach that of the
clones in the optimal ancilla-based one-to-two phase-covariant cloning and
telecloning, i.e., the limitation of quantum mechanics. More interestingly, it
is a nonmaximally entangled state rather than the maximally entangled state
that can be used to realize such a telecloning task.
| |
| 2009-08-01T14:50:01Z | | Genuine (k, m)-threshold controlled teleportation and its security | | We propose genuine ($k$, $m$)-threshold controlling schemes for controlled
teleportation via multi-particle entangled states, where the teleportation of a
quantum state from a sender (Alice) to a receiver (Bob) is under the control of
$m$ supervisors such that $k$ ($k\leq m$) or more of these supervisors can help
Bob recover the transferred state. By construction, anyone of our quantum
channels is a genuine multipartite entangled state of which any two parts are
inseparable. Their properties are compared and contrasted with those of the
well-known Greenberger-Horne-Zeilinger, W, and linear cluster states, and also
several other genuine multipartite entangled states recently introduced in
literature. We show that our schemes are secure against both Bob's dishonesty
and supervisors' treacheries. For the latter case, the game theory is utilized
to prove that supervisors' cheats can be well prevented. In addition to their
practical importance, our schemes are also useful in seeking and exploring
genuine multipartite entangled states and opening another perspective for the
applications of the game theory in quantum information science.
| |
| 2011-06-04T07:25:25Z | | Remote information concentration and multipartite entanglement in
multilevel systems | | Remote information concentration (RIC) in $d$-level systems (qudits) is
studied. It is shown that the quantum information initially distributed in
three spatially separated qudits can be remotely and deterministically
concentrated to a single qudit via an entangled channel without performing any
global operations. The entangled channel can be different types of genuine
multipartite pure entangled states which are inequivalent under local
operations and classical communication. The entangled channel can also be a
mixed entangled state, even a bound entangled state which has a similar form to
the Smolin state, but has different features from the Smolin state. A common
feature of all these pure and mixed entangled states is found, i.e., they have
$d^2$ common commuting stabilizers. The differences of qudit-RIC and qubit-RIC
($d=2$) are also analyzed.
| |
| 2013-02-04T09:30:26Z | | Many-to-one remote information concentration for qudits and multipartite
entanglement | | Telecloning and its reverse process, referred to as remote information
concentration (RIC), have attracted considerable interest because of their
potential applications in quantum-information processing. We here present a
general scheme for RIC in $d$-level systems (qudits), in which the quantum
information initially distributed in many spatially separated qudits can be
remotely and deterministically concentrated to a single qudit via an entangled
channel without performing any global operations. We show that the entangled
channel of RIC can be different types of entangled states, including mixed
states as well as pure ones. More interestingly, these mixed states include a
bound entangled state which has a similar form to the generalized Smolin state
but has different characteristics from it. We also show that there exists a
multipartite entangled state which can be used to implement both telecloning
and RIC in the two-level system.
| |
| 2011-12-28T15:36:00Z | | Photonic two-qubit parity gate with tiny cross-Kerr nonlinearity | | The cross-Kerr nonlinearity (XKNL) effect can induce efficient photon
interactions in principle with which photonic multiqubit gates can be performed
using far fewer physical resources than linear optical schemes. Unfortunately,
it is extremely challenging to generate giant cross-Kerr nonlinearities. In
recent years, much effort has been made to perform multiqubit gates via weak
XKNLs. However, the required nonlinearity strengths are still difficult to
achieve in the experiment. We here propose an XKNL-based scheme for realizing a
two-photon polarization-parity gate, a universal two-qubit gate, in which the
required strength of the nonlinearity could be orders of magnitude weaker than
those required for previous schemes. The scheme utilizes a ring cavity fed by a
coherent state as a quantum information bus which interacts with a path mode of
the two polarized photons (qubits). The XKNL effect makes the bus pick up a
phase shift dependent on the photon number of the path mode. Even when the
potential phase shifts are very small they can be effectively measured using
photon-number resolving detectors, which accounts for the fact that our scheme
can work in the regime of tiny XKNL. The measurement outcome reveals the parity
(even parity or odd parity) of the two polarization qubits.
| |
| 2013-04-10T01:06:45Z | | Longitudinal Single Bunch Instability Study on BEPCII | | In order to study the single bunch longitudinal instability in BEPCII,
experiments on the positron ring (BPR) for the bunch lengthening phenomenon
were made. By analyzing the experimental data based on Gao's theory, the
longitudinal loss factor for the bunch are obtained. Also, the total wake
potential and the beam current threshold are estimated.
| |
|
|