5,974 research outputs found
Oblivious remote state preparation
We consider remote state preparation protocols for a set of pure states whose
projectors form a basis for operators acting on the input Hilbert space. If a
protocol (1) uses only forward communication and entanglement, (2)
deterministically prepares an exact copy of the state, and (3) does so
obliviously -- without leaking further information about the state to the
receiver -- then the protocol can be modified to require from the sender only a
single specimen of the state. Furthermore, the original protocol and the
modified protocol use the same amount of classical communication. Thus, under
the three conditions stated, remote state preparation requires at least as much
classical communication as teleportation, as Lo has conjectured [PRA 62 (2000)
012313], which is twice the expected classical communication cost of some
existing nonoblivious protocols
Faithful remote state preparation using finite classical bits and a non-maximally entangled state
We present many ensembles of states that can be remotely prepared by using
minimum classical bits from Alice to Bob and their previously shared entangled
state and prove that we have found all the ensembles in two-dimensional case.
Furthermore we show that any pure quantum state can be remotely and faithfully
prepared by using finite classical bits from Alice to Bob and their previously
shared nonmaximally entangled state though no faithful quantum teleportation
protocols can be achieved by using a nonmaximally entangled state.Comment: 6 page
Remote State Preparation
Quantum teleportation uses prior entanglement and forward classical
communication to transmit one instance of an unknown quantum state. Remote
state preparation (RSP) has the same goal, but the sender knows classically
what state is to be transmitted. We show that the asymptotic classical
communication cost of RSP is one bit per qubit - half that of teleportation -
and becomes even less when transmitting part of a known entangled state. We
explore the tradeoff between entanglement and classical communication required
for RSP, and discuss RSP capacities of general quantum channels.Comment: 4 pages including 1 epsf figure; v3 has an additional author and
discusses relation to work of Devetak and Berger (quant-ph/0102123); v4
improves low-entanglement protocols without back communication to perform as
well as low-entanglement protocols with back communication; v5 (journal
version) has a few small change
Generalized Remote Preparation of Arbitrary -qubit Entangled States via Genuine Entanglements
Herein, we present a feasible, general protocol for quantum communication
within a network via generalized remote preparation of an arbitrary -qubit
entangled state designed with genuine tripartite
Greenberger--Horne--Zeilinger-type entangled resources. During the
implementations, we construct novel collective unitary operations; these
operations are tasked with performing the necessary phase transfers during
remote state preparations. We have distilled our implementation methods into a
five-step procedure, which can be used to faithfully recover the desired state
during transfer. Compared to previous existing schemes, our methodology
features a greatly increased success probability. After the consumption of
auxiliary qubits and the performance of collective unitary operations, the
probability of successful state transfer is increased four-fold and eight-fold
for arbitrary two- and three-qubit entanglements when compared to other methods
within the literature, respectively. We conclude this paper with a discussion
of the presented scheme for state preparation, including: success
probabilities, reducibility and generalizability.Comment: 16 pages, 3 figures, 3 tables, Accepted to Entrop
Optimal superdense coding of entangled states
We present a one-shot method for preparing pure entangled states between a
sender and a receiver at a minimal cost of entanglement and quantum
communication. In the case of preparing unentangled states, an earlier paper
showed that a 2n-qubit quantum state could be communicated to a receiver by
physically transmitting only n+o(n) qubits in addition to consuming n ebits of
entanglement and some shared randomness. When the states to be prepared are
entangled, we find that there is a reduction in the number of qubits that need
to be transmitted, interpolating between no communication at all for maximally
entangled states and the earlier two-for-one result of the unentangled case,
all without the use of any shared randomness. We also present two applications
of our result: a direct proof of the achievability of the optimal superdense
coding protocol for entangled states produced by a memoryless source, and a
demonstration that the quantum identification capacity of an ebit is two
qubits.Comment: Final Version. Several technical issues clarifie
Resources required for exact remote state preparation
It has been shown [M.-Y. Ye, Y.-S. Zhang, and G.-C. Guo, Phys. Rev. A 69,
022310 (2004)] that it is possible to perform exactly faithful remote state
preparation using finite classical communication and any entangled state with
maximal Schmidt number. Here we give an explicit procedure for performing this
remote state preparation. We show that the classical communication required for
this scheme is close to optimal for remote state preparation schemes of this
type. In addition we prove that it is necessary that the resource state have
maximal Schmidt number.Comment: 7 pages, 1 figur
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