81,682 research outputs found
Efficient quantum teleportation of unknown qubit based on DV-CV interaction mechanism
We propose and develop theory of quantum teleportation of unknown qubit based
on interaction mechanism between discrete-variable (DV) and continuous-variable
(CV) states on highly transmissive beam splitter (HTBS). This DV-CV interaction
mechanism is based on simultaneous displacement of the discrete-variable state
on equal in absolute value but opposite in sign displacement amplitudes by
coherent components of the hybrid, in such a way that all the information about
the displacement amplitudes is lost with subsequent registration of photons in
the auxiliary mode
Continuous variable entanglement on a chip
Encoding quantum information in continuous variables (CV)---as the quadrature
of electromagnetic fields---is a powerful approach to quantum information
science and technology. CV entanglement---light beams in
Einstein-Podolsky-Rosen (EPR) states---is a key resource for quantum
information protocols; and enables hybridisation between CV and single photon
discrete variable (DV) qubit systems. However, CV systems are currently limited
by their implementation in free-space optical networks: increased complexity,
low loss, high-precision alignment and stability, as well as hybridisation,
demand an alternative approach. Here we show an integrated photonic
implementation of the key capabilities for CV quantum technologies---generation
and characterisation of EPR beams in a photonic chip. Combined with integrated
squeezing and non-Gaussian operation, these results open the way to universal
quantum information processing with light
Remote preparation of continuous-variable qubits using loss-tolerant hybrid entanglement of light
Transferring quantum information between distant nodes of a network is a key
capability. This transfer can be realized via remote state preparation where
two parties share entanglement and the sender has full knowledge of the state
to be communicated. Here we demonstrate such a process between heterogeneous
nodes functioning with different information encodings, i.e., particle-like
discrete-variable optical qubits and wave-like continuous-variable ones. Using
hybrid entanglement of light as a shared resource, we prepare arbitrary
coherent-state superpositions controlled by measurements on the distant
discrete-encoded node. The remotely prepared states are fully characterized by
quantum state tomography and negative Wigner functions are obtained. This work
demonstrates a novel capability to bridge discrete- and continuous-variable
platforms
Classifying, quantifying, and witnessing qudit-qumode hybrid entanglement
Recently, several hybrid approaches to quantum information emerged which
utilize both continuous- and discrete-variable methods and resources at the
same time. In this work, we investigate the bipartite hybrid entanglement
between a finite-dimensional, discrete-variable quantum system and an
infinite-dimensional, continuous-variable quantum system. A classification
scheme is presented leading to a distinction between pure hybrid entangled
states, mixed hybrid entangled states (those effectively supported by an
overall finite-dimensional Hilbert space), and so-called truly hybrid entangled
states (those which cannot be described in an overall finite-dimensional
Hilbert space). Examples for states of each regime are given and entanglement
witnessing as well as quantification are discussed. In particular, using the
channel map of a thermal photon noise channel, we find that true hybrid
entanglement naturally occurs in physically important settings. Finally,
extensions from bipartite to multipartite hybrid entanglement are considered.Comment: 15 pages, 10 figures, final published version in Physical Review
General phase spaces: from discrete variables to rotor and continuum limits
We provide a basic introduction to discrete-variable, rotor, and
continuous-variable quantum phase spaces, explaining how the latter two can be
understood as limiting cases of the first. We extend the limit-taking
procedures used to travel between phase spaces to a general class of
Hamiltonians (including many local stabilizer codes) and provide six examples:
the Harper equation, the Baxter parafermionic spin chain, the Rabi model, the
Kitaev toric code, the Haah cubic code (which we generalize to qudits), and the
Kitaev honeycomb model. We obtain continuous-variable generalizations of all
models, some of which are novel. The Baxter model is mapped to a chain of
coupled oscillators and the Rabi model to the optomechanical radiation pressure
Hamiltonian. The procedures also yield rotor versions of all models, five of
which are novel many-body extensions of the almost Mathieu equation. The toric
and cubic codes are mapped to lattice models of rotors, with the toric code
case related to U(1) lattice gauge theory.Comment: 22 pages, 3 figures; part of special issue on Rabi model; v2 minor
change
Beyond the RCT: Integrating Rigor and Relevance to Evaluate the Outcomes of Domestic Violence Programs
Programs for domestic violence (DV) victims and their families have grown exponentially over the last four decades. The evidence demonstrating the extent of their effectiveness, however, often has been criticized as stemming from studies lacking scientific rigor. A core reason for this critique is the widespread belief that credible evidence can derive only from research grounded in randomized control trials (RCTs). Although the RCT method has its strengths, we argue that it is rarely an optimalâor even a possibleâapproach for evaluating multifaceted DV programs. This article reviews the reasons that RCT is a poor fit for such programs and argues that a more inclusive conceptualization of credible evidence is critical to expanding our knowledge base about how DV programs affect survivorsâ safety and well-being
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