56 research outputs found
Photon Sorting, Efficient Bell Measurements and a Deterministic CZ Gate using a Passive Two-level Nonlinearity
Although the strengths of optical non-linearities available experimentally
have been rapidly increasing in recent years, significant challenges remain to
using such non-linearities to produce useful quantum devices such as efficient
optical Bell state analysers or universal quantum optical gates. Here we
describe a new approach that avoids the current limitations by combining strong
non-linearities with active Gaussian operations in efficient protocols for Bell
state analysers and Controlled-Sign gates
Single-photon nonlinear optics with a quantum dot in a waveguide
Strong nonlinear interactions between photons enable logic operations for
both classical and quantum-information technology. Unfortunately, nonlinear
interactions are usually feeble and therefore all-optical logic gates tend to
be inefficient. A quantum emitter deterministically coupled to a propagating
mode fundamentally changes the situation, since each photon inevitably
interacts with the emitter, and highly correlated many-photon states may be
created . Here we show that a single quantum dot in a photonic-crystal
waveguide can be utilized as a giant nonlinearity sensitive at the
single-photon level. The nonlinear response is revealed from the intensity and
quantum statistics of the scattered photons, and contains contributions from an
entangled photon-photon bound state. The quantum nonlinearity will find
immediate applications for deterministic Bell-state measurements and
single-photon transistors and paves the way to scalable waveguide-based
photonic quantum-computing architectures
Spin-photon interface and spin-controlled photon switching in a nanobeam waveguide
Access to the electron spin is at the heart of many protocols for integrated
and distributed quantum-information processing [1-4]. For instance, interfacing
the spin-state of an electron and a photon can be utilized to perform quantum
gates between photons [2,5] or to entangle remote spin states [6-9].
Ultimately, a quantum network of entangled spins constitutes a new paradigm in
quantum optics [1]. Towards this goal, an integrated spin-photon interface
would be a major leap forward. Here we demonstrate an efficient and optically
programmable interface between the spin of an electron in a quantum dot and
photons in a nanophotonic waveguide. The spin can be deterministically prepared
with a fidelity of 96\%. Subsequently the system is used to implement a
"single-spin photonic switch", where the spin state of the electron directs the
flow of photons through the waveguide. The spin-photon interface may enable
on-chip photon-photon gates [2], single-photon transistors [10], and efficient
photonic cluster state generation [11]
An In-Vitro Study on the Release of Fluoride from Two Restorative Materials and Their Rechargeability after Exposure to Daily 1000 ppm Fluoride
Statement of Problem: Since the fluoride releases from materials with the property of releasing fluoride are decreasing gradually, it seems that probably the material rechargeability is more important than their long-term fluoride release.Purpose: the objective of this study was to asses the fluoride release and rechargeability of 2 types of fluoride releasing restorative materials, a resin modified glass ionomer(Vitremer) and a compomer (Compoglass F), after exposure to daily NaF solutionscontaining 1000 ppm F, for 1 minute.Materials and Methods: Twelve discs ( 8 mm Ă2 mm) of each of the materials were fabricated, and divided into 2 groups (test and control). All discs were stored in 4 mL artificial saliva at 37°C. In group 1 (N=6), the specimens were immersed in artificialsaliva which was changed daily for 25 days. In group 2 (N=6), in addition to receiving the same treatment as group 1, the specimens were immersed in NaF solution (1000ppm F, ph=6.9) for 1 minute before daily saliva change. A potentiometer was used to determine the amount of fluoride released on days 1, 2, 3, 5, 10, 15, 20 and 25, after the daily saliva change, in all study groups. Data were analyzed by the t-student test after confirmation of the equality of variances by Levenâs test.Results: Both materials continued releasing fluoride throughout the whole study period. For each material, the release was highest on day one. During the first 3 days,glass ionomer released significantly higher amounts of fluoride as compared to compomer (p<0.05); but afterwards, there was no significant difference between the 2 materials (p>0.05). After exposure to NaF solution, none of the materials showed statistically significant rechargeability (p>0.05) and the amount of fluoride-releasecontinued to drop during the study period in similar patterns for both the test and the control groups.Conclusion: It may be concluded that rechargeability of glass ionomer and compomer,using daily neutral fluoride mouth rinses and toothpastes does not occur in reliable amounts
Sanitation Network Sulfide Modeling as a Tool for Asset Management. The Case of the City of Murcia (Spain)
- âŠ