Search results for "Quantum channel"
showing 10 items of 33 documents
Creating quantum correlations through local non-unitary memoryless channels
2012
We show that two qubits, initially in a fully classical state, can develop significant quantum correlations as measured by the quantum discord (QD) under the action of a local memoryless noise (specifically we consider the case of a Markovian amplitude-damping channel). This is analytically proven after deriving in a compact form the QD for the class of separable states involved in such a process. We provide a picture in the Bloch sphere that unambiguously highlights the physical mechanism behind the effect regardless of the specific measure of QCs adopted.
Scalable and effective multi-level entangled photon states: a promising tool to boost quantum technologies
2021
Abstract Multi-level (qudit) entangled photon states are a key resource for both fundamental physics and advanced applied science, as they can significantly boost the capabilities of novel technologies such as quantum communications, cryptography, sensing, metrology, and computing. The benefits of using photons for advanced applications draw on their unique properties: photons can propagate over long distances while preserving state coherence, and they possess multiple degrees of freedom (such as time and frequency) that allow scalable access to higher dimensional state encoding, all while maintaining low platform footprint and complexity. In the context of out-of-lab use, photon generation…
Removing phase ambiguity in fiber-based interferometers for coherent time-bin operations
2019
Time is a practical and robust degree of freedom for the encoding of quantum information. Qubits encoded in so-called 'time-bins', allowing a discrete superposition of two potential arrival times, have their entanglement preserved even over long propagation distances in standard fiber networks [1]. Time has also been used for the preparation of more complex quantum systems, such as hyper-entangled and cluster states [2]. These qualities put time-bin encoding at the center of applications ranging from quantum state preparation through to quantum communications and information processing. One of the hallmarks of the scheme is that a nonlinear element has to be pumped with phase-coherent doubl…
Deterministic quantum teleportation of photonic quantum bits by a hybrid technique.
2014
The continuous-variable teleportation of a discrete-variable, photonic qubit is deterministic and allows for faithful qubit transfer even with imperfect continuous-variable entangled states: for four qubits, the overall transfer fidelities all exceed the classical limit of teleportation. Quantum teleportation is one of the most important elementary protocols in quantum information processing. Previous studies have achieved quantum teleportation, but usually randomly and at low rates. Two groups reporting in this issue of Nature have used contrasting methods to achieve the same aim —more efficient quantum teleportation. Takeda et al. describe the experimental realization of fully determinist…
Indistinguishability as a quantum information resource by localized measurements
2019
Quantum networks are typically made of identical subsystems. Exploiting indistinguishability as a direct quantum resource would thus be highly desirable. We show this is achievable by spatially localized measurements, enabling teleportation and entanglement swapping protocols.
Kerr Combs and Telecommunications Components for the Generation and High-Dimensional Quantum Processing of d-Level Cluster States
2019
Large and complex optical quantum states are a key resource for fundamental science and applications such as quantum communications, information processing, and metrology. In this context, cluster states are a particularly important class because they enable the realization of universal quantum computers by means of the so-called ‘one-way’ scheme, where processing operations are performed through measurements on the state. While two-level (i.e. qubit) cluster states have been realized thus far, further boosting this computational resource by increasing the number of particles comes at the price of significantly reduced coherence time and detection rates, as well as increased sensitivity to …
Hybrid quantum teleportation
2013
Quantum teleportation allows for the transfer of arbitrary, in principle, unknown quantum states from a sender to a spatially distant receiver, who share an entangled state and can communicate classically. It is the essence of many sophisticated protocols for quantum communication and computation. In order to realize flying qubits in these schemes, photons are an optimal choice. However, teleporting a photonic qubit has been limited due to experimental inefficiencies and restrictions. Major disadvantages have been the probabilistic nature of both entangled resource states and linear-optics Bell-state measurements (BSM), as well as the need for post-selecting the successful events by destroy…
Role of information backflow in the emergence of quantum Darwinism
2019
Quantum Darwinism attempts to explain the emergence of objective reality of the state of a quantum system in terms of redundant information about the system acquired by independent non interacting fragments of the environment. The consideration of interacting environmental elements gives rise to a rich phenomenology, including the occurrence of non-Markovian features, whose effects on objectification {\it a' la} quantum Darwinism needs to be fully understood. We study a model of local interaction between a simple quantum system and a multi-mode environment that allows for a clear investigation of the interplay between information trapping and propagation in the environment and the emergence…
Solitons ofq-deformed quantum lattices and the quantum soliton
2001
We use the classical N-soliton solution of a q-deformed lattice, the Maxwell-Bloch (MB) lattice, which we reported recently (Rybin A V, Varzugin G G, Timonen J and Bullough R K Year 2001 J. Phys. A: Math. Gen. 34 157) in order, ultimately, to fully comprehend the `quantum soliton'. This object may be the source of a new information technology (Abram I 1999 Quantum solitons Phys. World 21-4). We suggested in Rybin et al 2001 that a natural quantum mechanical matrix element of the q-deformed quantum MB lattice becomes in a suitable limit the classical 1-soliton solution of the classical q-deformed MB lattice explicitly derived by a variant of the Darboux-Backlund method. The classical q-defor…