4,333 research outputs found
Tomography of a displacement photon counter for discrimination of single-rail optical qubits
We investigate the performance of a Kennedy receiver, which is known as a
beneficial tool in optical coherent communications, to the quantum state
discrimination of the two superpositions of vacuum and single photon states
corresponding to the eigenstates in the single-rail encoding of
photonic qubits. We experimentally characterize the Kennedy receiver in
vacuum-single photon two-dimensional space using quantum detector tomography
and evaluate the achievable discrimination error probability from the
reconstructed measurement operators. We furthermore derive the minimum error
rate obtainable with Gaussian transformations and homodyne detection. Our proof
of principle experiment shows that the Kennedy receiver can achieve a
discrimination error surpassing homodyne detection
Assessments of macroscopicity for quantum optical states
With the slow but constant progress in the coherent control of quantum
systems, it is now possible to create large quantum superpositions. There has
therefore been an increased interest in quantifying any claims of
macroscopicity. We attempt here to motivate three criteria which we believe
should enter in the assessment of macroscopic quantumness: The number of
quantum fluctuation photons, the purity of the states, and the ease with which
the branches making up the state can be distinguished
Architecture and noise analysis of continuous variable quantum gates using two-dimensional cluster states
Due to its unique scalability potential, continuous variable quantum optics
is a promising platform for large scale quantum computing and quantum
simulation. In particular, very large cluster states with a two-dimensional
topology that are suitable for universal quantum computing and quantum
simulation can be readily generated in a deterministic manner, and routes
towards fault-tolerance via bosonic quantum error-correction are known. In this
article we propose a complete measurement-based quantum computing architecture
for the implementation of a universal set of gates on the recently generated
two-dimensional cluster states [1,2]. We analyze the performance of the various
quantum gates that are executed in these cluster states as well as in other
two-dimensional cluster states (the bilayer-square lattice and quad-rail
lattice cluster states [3,4]) by estimating and minimizing the associated
stochastic noise addition as well as the resulting gate error probability. We
compare the four different states and find that, although they all allow for
universal computation, the quad-rail lattice cluster state performs better than
the other three states which all exhibit similar performance
Super sensitivity and super resolution with quantum teleportation
We propose a method for quantum enhanced phase estimation based on continuous
variable (CV) quantum teleportation. The phase shift probed by a coherent state
can be enhanced by repeatedly teleporting the state back to interact with the
phase shift again using a supply of two-mode squeezed vacuum states. In this
way, both super resolution and super sensitivity can be obtained due to the
coherent addition of the phase shift. The protocol enables Heisenberg limited
sensitivity and super- resolution given sufficiently strong squeezing. The
proposed method could be implemented with current or near-term technology of CV
teleportation.Comment: 5 pagers, 3 figure
Hybrid quantum information processing
The development of quantum information processing has traditionally followed
two separate and not immediately connected lines of study. The main line has
focused on the implementation of quantum bit (qubit) based protocols whereas
the other line has been devoted to implementations based on high-dimensional
Gaussian states (such as coherent and squeezed states). The separation has been
driven by the experimental difficulty in interconnecting the standard
technologies of the two lines. However, in recent years, there has been a
significant experimental progress in refining and connecting the technologies
of the two fields which has resulted in the development and experimental
realization of numerous new hybrid protocols. In this Review, we summarize
these recent efforts on hybridizing the two types of schemes based on discrete
and continuous variables.Comment: 13 pages, 6 figure
Who are the actors and what are the factors that are used in models to map forest fire susceptibility? A systematic review
In the last decades, natural fire regimes have experienced significant alterations in terms of intensity, frequency and severity in fire prone regions of the world. Modelling forest fire susceptibility has been essential in identifying areas of high risk to minimize threats to natural resources, biodiversity and life. There have been significant improvements in forest fire susceptibility modelling over the past two decades 2001â2021. In this study, we conducted a systematic literature review of literature covering forest fire susceptibility modelling published during this period. The review provides insights on the main themes of forest fire susceptibility modelling research, the main base input factors used in models to map forest fire susceptibility, the main researchers, the areas where this type of research were implemented, technology and models used. It also highlights collaboration opportunities, and regions, such as Central America and Africa, where mapping of forest fire susceptibility is needed. We argue that such knowledge is crucial in order to identify critical factors and opportunities which can aid in improving factor selection and forest fire management.Peer Reviewe
The Role of Implementation Leadership in Driving Organizational Innovation â Revisiting a Classic
In this article, we discuss the importance of leadership when implementing innovations. A particular focus point is the seminal work by Everett Rogers on the spread and upkeep of new ideas. Furthermore, we examine current scientific works on implementation leadership in relation to initiating and maintaining health enhancing physical activity programs. Among other things, we point out how many people and groups are sympathetic towards new innovations if they meet a recognized need, contribute to relevant developments, make sense in concrete situations, and can be mastered individually and collectively. Implementation leaders need to ensure that premises such as these are met while taking into account that innovations are absorbed at different speeds and ways by different stakeholders. Rogers\u27 five adopter categories can be used by implementation leaders to develop effective change communication that is meaningful to differentiated groups. First-line leaders can, for instance, use their dense knowledge of the organization\u27s needs and circumstances to support staff and manage stakeholders during the implementation process. Delegating substantial implementation responsibility to early adopters can also prove beneficial in keeping the process on track
Coordination work â Tuning and timing rice production in Burkina Faso
Agricultural growth poles and development corridors are key instruments for fostering economic growth in rural areas and widely employed across the African continent. This paper contributes to the growing body of scholarship that empirically investigates how these large-scale spatial development strategies âhit the groundâ. Drawing on ethnographic research within the BagrĂ© Growth Pole Project in Burkina Faso and focusing on its key sector, rice, we develop the notion of coordination work. Coordination work captures the quotidian dimension of a growth pole project that is the instruments and interventions aimed at aligning different actors, activities, and arrangements in the project zone. Deploying a practice theoretical lens, we empirically unfold three modes of coordination work, namely the work of agricultural advisors on demonstration fields, consultancy support to farmer groups and unions, and the setting up of a binding agricultural calendar. We contend that a focus on coordination work illuminates the underlying assumptions and effects of distinct measures and instruments while also pointing to the cross connections between them. Ultimately, we show how specific project components change socio-ecological rhythms by tuning and timing practices at the center of megaprojects.Peer Reviewe
Measurement-induced macroscopic superposition states in cavity optomechanics
We present a novel proposal for generating quantum superpositions of
macroscopically distinct states of a bulk mechanical oscillator, compatible
with existing optomechanical devices operating in the readily achievable
bad-cavity limit. The scheme is based on a pulsed cavity optomechanical quantum
non-demolition (QND) interaction, driven by displaced non-Gaussian states, and
measurement-induced feedback, avoiding the need for strong single-photon
optomechanical coupling. Furthermore, we show that single-quadrature cooling of
the mechanical oscillator is sufficient for efficient state preparation, and we
outline a three-pulse protocol comprising a sequence of QND interactions for
squeezing-enhanced cooling, state preparation, and tomography.Comment: 7 pages, 5 figure
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