18,407 research outputs found
Extracting Classical Correlations from a Bipartite Quantum System
In this paper we discuss the problem of splitting the total correlations for
a bipartite quantum state described by the Von Neumann mutual information into
classical and quantum parts. We propose a measure of the classical correlations
as the difference between the Von Neumann mutual information and the relative
entropy of entanglement. We compare this measure with different measures
proposed in the literature.Comment: 5 pages, 1 figur
Remote information concentration using a bound entangled state
Remote information concentration, the reverse process of quantum telecloning,
is presented. In this scheme, quantum information originally from a single
qubit, but now distributed into three spatially separated qubits, is remotely
concentrated back to a single qubit via an initially shared entangled state
without performing any global operations. This entangled state is an unlockable
bound entangled state and we analyze its properties.Comment: 4 pages, 2 figure
Teleportation as a Depolarizing Quantum Channel, Relative Entropy and Classical Capacity
We show that standard teleportation with an arbitrary mixed state resource is
equivalent to a generalized depolarizing channel with probabilities given by
the maximally entangled components of the resource. This enables the usage of
any quantum channel as a generalized depolarizing channel without additional
twirling operations. It also provides a nontrivial upper bound on the
entanglement of a class of mixed states. Our result allows a consistent and
statistically motivated quantification of teleportation success in terms of the
relative entropy and this quantification can be related to a classical
capacity.Comment: Version published in Phys. Rev. Let
Quantum superposition of multiple clones and the novel cloning machine
we envisage a novel quantum cloning machine, which takes an input state and
produces an output state whose success branch can exist in a linear
superposition of multiple copies of the input state and the failure branch
exist in a superposition of composite state independent of the input state. We
prove that unknown non-orthogonal states chosen from a set can evolve
into a linear superposition of multiple clones by a unitary process if and only
if the states are linearly independent. We derive a bound on the success
probability of the novel cloning machine. We argue that the deterministic and
probabilistic clonings are special cases of our novel cloning machine.Comment: Two column, 5 pages, Latex, some additions, minor changes. Phys. Rev.
Lett. (To appear, 1999
Entangled Rings
Consider a ring of N qubits in a translationally invariant quantum state. We
ask to what extent each pair of nearest neighbors can be entangled. Under
certain assumptions about the form of the state, we find a formula for the
maximum possible nearest-neighbor entanglement. We then compare this maximum
with the entanglement achieved by the ground state of an antiferromagnetic ring
consisting of an even number of spin-1/2 particles. We find that, though the
antiferromagnetic ground state does not maximize the nearest-neighbor
entanglement relative to all other states, it does so relative to other states
having zero z-component of spin.Comment: 19 pages, no figures; v2 includes new results; v3 corrects a
numerical error for the case N=
Caveolin-1 is a risk factor for postsurgery metastasis in preclinical melanoma models
Melanomas are highly lethal skin tumours that are frequently treated by surgical resection. However, the efficacy of such procedures is often limited by tumour recurrence and metastasis. Caveolin-1 (CAV1) has been attributed roles as a tumour suppressor, although in late-stage tumours, its presence is associated with enhanced metastasis. The expression of this protein in human melanoma development and particularly how the presence of CAV1 affects metastasis after surgery has not been defined. CAV1 expression in human melanocytes and melanomas increases with disease progression and is highest in metastatic melanomas. The effect of increased CAV1 expression can then be evaluated using B16F10 murine melanoma cells injected into syngenic immunocompetent C57BL/6 mice or human A375 melanoma cells injected into immunodeficient B6Rag1−/− mice. Augmented CAV1 expression suppresses tumour formation upon a subcutaneous injection, but enhances lung metastasis of cells injected into the tail vein in both models. A procedure was initially developed using B16F10 melanoma cells in C57BL/6 mice to mimic better the situation in patients undergoing surgery. Subcutaneous tumours of a defined size were removed surgically and local tumour recurrence and lung metastasis were evaluated after another 14 days. In this postsurgery setting, CAV1 presence in B16F10 melanomas favoured metastasis to the lung, although tumour suppression at the initial site was still evident. Similar results were obtained when evaluating A375 cells in B6Rag1−/− mice. These results implicate CAV1 expression in melanomas as a marker of poor prognosis for patients undergoing surgery as CAV1 expression promotes experimental lung metastasis in two different preclinical models
- …