4,428 research outputs found
Quantum-circuit guide to optical and atomic interferometry
Atomic (qubit) and optical or microwave (modal) phase-estimation protocols
are placed on the same footing in terms of quantum-circuit diagrams. Circuit
equivalences are used to demonstrate the equivalence of protocols that achieve
the Heisenberg limit by employing entangled superpositions of Fock states, such
as N00N states. The key equivalences are those that disentangle a circuit so
that phase information is written exclusively on a mode or modes or on a qubit.
The Fock-state-superposition phase-estimation circuits are converted to use
entangled coherent-state superpositions; the resulting protocols are more
amenable to realization in the lab, particularly in a qubit/cavity setting at
microwave frequencies.Comment: To appear in Optics Communications special issue in memory of
Krzysztof Wodkiewic
Jaynes Cummings treatment of superconducting resonators with dielectric loss due to two-level systems
We perform a quantum mechanical analysis of superconducting resonators
subject to dielectric loss arising from charged two-level systems. We present
numerical and analytical descriptions of the dynamics of energy decay from the
resonator within the Jaynes-Cummings model. Our analysis allows us to
distinguish the strong and weak coupling regimes of the model and to describe
within each regime cases where the two-level system is unsaturated or
saturated. We find that the quantum theory agrees with the classical model for
weak coupling. However, for strong coupling the quantum theory predicts lower
loss than the classical theory in the unsaturated regime. Also, in contrast to
the classical theory, the photon number at which saturation occurs in the
strong coupling quantum theory is independent of the coupling between the
resonator and the two-level system.Comment: 9 pages, 8 figure
Topology Classes of Flat U(1) Bundles and Diffeomorphic Covariant Representations of the Heisenberg Algebra
The general construction of self-adjoint configuration space representations
of the Heisenberg algebra over an arbitrary manifold is considered. All such
inequivalent representations are parametrised in terms of the topology classes
of flat U(1) bundles over the configuration space manifold. In the case of
Riemannian manifolds, these representations are also manifestly diffeomorphic
covariant. The general discussion, illustrated by some simple examples in non
relativistic quantum mechanics, is of particular relevance to systems whose
configuration space is parametrised by curvilinear coordinates or is not simply
connected, which thus include for instance the modular spaces of theories of
non abelian gauge fields and gravity.Comment: 22 pages, no figures, plain LaTeX file; changes only in details of
affiliation and financial suppor
A Comparison of the Values Between Male Athletic Participants and Non-Participants Attending St. Boniface Diocesan High School
The purpose of the study was to compare the values of selected high school male athletic participants and non- participants enrolled in grades ten to twelve at St. Boniface Diocesan High School. The instrument used was the Allport- Vernon-Lindzey Study of Values. The purpose of the test was to measure the relative prominence of six basic interests as motives in personality.
The population chosen for this research study was the finite population of the male students enrolled at St. Boniface Diocesan High School during the 1974-75 school year. Hie population was divided into two strata: athletic partici pants and non-participants. A random sample of stibjects was then taken from each stratum, using random table of numbers.
The tests were hand scored and points assigned to each of the six measured values. Means and standard deviations were calculated for each variable, for each of the two groups The means and standard deviations wei\u27e then compared between the participant, non-participant and national norm groups. The t test was calculated to determine the significance of the comparisons.
There were no significant differences when the t test was calculated at .05 level of significance and 59 degrees of freedom between the participant and non-participant, group.
There was a significant difference between the nonparticipant group and the national norm group on the social scale. The t test calculations at .05 level of significance and 29 degrees of freedom showed that the non-participants scored significantly higher on the social scale. There were significant differences between the participants and the national norm group. The t test calculations at .05 level of significance and 29 degrees of freedom showed that the participants scored higher on the social scale and lower on the theoretical and religious scale than the national norm grouo
The Coherent Crooks Equality
This chapter reviews an information theoretic approach to deriving quantum
fluctuation theorems. When a thermal system is driven from equilibrium, random
quantities of work are required or produced: the Crooks equality is a classical
fluctuation theorem that quantifies the probabilities of these work
fluctuations. The framework summarised here generalises the Crooks equality to
the quantum regime by modeling not only the driven system but also the control
system and energy supply that enables the system to be driven. As is reasonably
common within the information theoretic approach but high unusual for
fluctuation theorems, this framework explicitly accounts for the energy
conservation using only time independent Hamiltonians. We focus on explicating
a key result derived by Johan {\AA}berg: a Crooks-like equality for when the
energy supply is allowed to exist in a superposition of energy eigenstates
states.Comment: 11 pages, 3 figures; Chapter for the book "Thermodynamics in the
Quantum Regime - Recent Progress and Outlook", eds. F. Binder, L. A. Correa,
C. Gogolin, J. Anders and G. Adess
Concentration and purification of entanglement for qubit systems with ancillary cavity fields
We propose schemes for entanglement concentration and purification for qubit
systems encoded in flying atomic pairs. We use a cavity-quantum electrodynamics
setting as the paradigmatic scenario within which our proposals can be
implemented. Maximally entangled pure states of qubits can be produced as a
result of our protocols. In particular, the concentration protocol yields Bell
states with the largest achievable theoretical probability while the
purification scheme produces arbitrarily pure Bell states. The requirements for
the implementation of these protocols are modest, within the state of the art,
and we address all necessary steps in two specific set-ups based on
experimentally mature microwave technology.Comment: 10 pages, 6 figure
Vacuum state truncation via the quantum Zeno effect
In the context of quantum state engineering we analyze the effect of
observation on nonlinear optical -photon Fock state generation. We show that
it is possible to truncate the vacuum component from an arbitrary photon number
superposition without modifying its remaining parts. In the course of the full
dynamical analysis of the effect of observation, it is also found that the Zeno
and the anti-Zeno effects repeat periodically. We discuss the close
relationship between vacuum state truncation and so-called "interaction-free"
measurement.Comment: 4 pages, 2 figures, LaTeX; TeX errors fixe
Mesocosm experiments reveal the impact of mosquito control measures on malaria vector life history and population dynamics
The impact of control measures on mosquito vector fitness and demography is usually estimated from bioassays or indirect variables in the field. Whilst indicative, neither approach is sufficient to quantify the potentially complex response of mosquito populations to combined interventions. Here, large replicated mesocosms were used to measure the population-level response of the malaria vector Anopheles arabiensis to long-lasting insecticidal nets (LLINs) when used in isolation, or combined with insecticidal eave louvers (EL), or treatment of cattle with the endectocide Ivermectin (IM). State-space models (SSM) were fit to these experimental data, revealing that LLIN introduction reduced adult mosquito survival by 91% but allowed population persistence. ELs provided no additional benefit, but IM reduced mosquito fecundity by 59% and nearly eliminated all populations when combined with LLINs. This highlights the value of IM for integrated vector control, and mesocosm population experiments combined with SSM for identifying optimal combinations for vector population elimination
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