37,808 research outputs found
Field correlations and effective two level atom-cavity systems
We analyse the properties of the second order correlation functions of the
electromagnetic field in atom-cavity systems that approximate two-level
systems. It is shown that a recently-developed polariton formalism can be used
to account for all the properties of the correlations, if the analysis is
extended to include two manifolds - corresponding to the ground state and the
states excited by a single photon - rather than just two levels.Comment: 4 pages, 2 figures, published versio
Dissipative production of a maximally entangled steady state
Entangled states are a key resource in fundamental quantum physics, quantum
cryp-tography, and quantum computation [1].To date, controlled unitary
interactions applied to a quantum system, so-called "quantum gates", have been
the most widely used method to deterministically create entanglement [2]. These
processes require high-fidelity state preparation as well as minimizing the
decoherence that inevitably arises from coupling between the system and the
environment and imperfect control of the system parameters. Here, on the
contrary, we combine unitary processes with engineered dissipation to
deterministically produce and stabilize an approximate Bell state of two
trapped-ion qubits independent of their initial state. While previous works
along this line involved the application of sequences of multiple
time-dependent gates [3] or generated entanglement of atomic ensembles
dissipatively but relied on a measurement record for steady-state entanglement
[4], we implement the process in a continuous time-independent fashion,
analogous to optical pumping of atomic states. By continuously driving the
system towards steady-state, the entanglement is stabilized even in the
presence of experimental noise and decoherence. Our demonstration of an
entangled steady state of two qubits represents a step towards dissipative
state engineering, dissipative quantum computation, and dissipative phase
transitions [5-7]. Following this approach, engineered coupling to the
environment may be applied to a broad range of experimental systems to achieve
desired quantum dynamics or steady states. Indeed, concurrently with this work,
an entangled steady state of two superconducting qubits was demonstrated using
dissipation [8].Comment: 25 pages, 5 figure
High performance photonic microwave filters based on a 50GHz optical soliton crystal Kerr micro-comb
We demonstrate a photonic radio frequency (RF) transversal filter based on an
integrated optical micro-comb source featuring a record low free spectral range
of 49 GHz yielding 80 micro-comb lines across the C-band. This record-high
number of taps, or wavelengths for the transversal filter results in
significantly increased performance including a QRF factor more than four times
higher than previous results. Further, by employing both positive and negative
taps, an improved out-of-band rejection of up to 48.9 dB is demonstrated using
Gaussian apodization, together with a tunable centre frequency covering the RF
spectra range, with a widely tunable 3-dB bandwidth and versatile dynamically
adjustable filter shapes. Our experimental results match well with theory,
showing that our transversal filter is a competitive solution to implement
advanced adaptive RF filters with broad operational bandwidths, high frequency
selectivity, high reconfigurability, and potentially reduced cost and
footprint. This approach is promising for applications in modern radar and
communications systems.Comment: 19 pages, 12 figures, 107 reference
EPIC 219217635: A Doubly Eclipsing Quadruple System Containing an Evolved Binary
We have discovered a doubly eclipsing, bound, quadruple star system in the
field of K2 Campaign 7. EPIC 219217635 is a stellar image with that
contains an eclipsing binary (`EB') with d and a second EB with
d. We have obtained followup radial-velocity (`RV')
spectroscopy observations, adaptive optics imaging, as well as ground-based
photometric observations. From our analysis of all the observations, we derive
good estimates for a number of the system parameters. We conclude that (1) both
binaries are bound in a quadruple star system; (2) a linear trend to the RV
curve of binary A is found over a 2-year interval, corresponding to an
acceleration, cm s; (3) small
irregular variations are seen in the eclipse-timing variations (`ETVs')
detected over the same interval; (4) the orbital separation of the quadruple
system is probably in the range of 8-25 AU; and (5) the orbital planes of the
two binaries must be inclined with respect to each other by at least
25. In addition, we find that binary B is evolved, and the cooler and
currently less massive star has transferred much of its envelope to the
currently more massive star. We have also demonstrated that the system is
sufficiently bright that the eclipses can be followed using small ground-based
telescopes, and that this system may be profitably studied over the next decade
when the outer orbit of the quadruple is expected to manifest itself in the ETV
and/or RV curves.Comment: Accepted for publication in MNRA
Fungsi Musik Pengiring Kesenian Baliatn Suku Dayak Kanayatn Kabupaten Landak
Baliatn is one of the ceremonial treatment performed to the accompaniment of music and its existence is still trusted by the community in the village of Authorship District of Hulu Mempawah Porcupine District. The purpose of this study was to mendeskripikan procession, wasp motif and function in a ceremony Baliatn. This research method is a method deskriftip and form of qualitative research. Source of research data is the motive and perpetrators of Ceremonies Baliatn wasp and hornet research data is motive, Procession Ceremony Baliatn and strains of musical instruments. Collecting data using observation, interviews and field data. Research tool is the researchers themselves as the main instrument, equipped with photo cameras, video, observation and field notes. Data analysis techniques with data reduction, data display and inference data. The results showed that Baliatn Ceremony procession takes place in four stages, namely, Baduduk, Lumpat, Bajampi and Nulak Batakng Park. Motif consists of hornet wasp Baduduk Nama'an Antu, Ka'Bawang, Jubata and Ngaranto. Ceremony music functions Baliatn is a means towards a state of trance for Pamaliatn artisan, artisan makes dance movement Pamaliatn semangkin agile dam summon ancestral spirits
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