Efficient Information Retrieval for Sensing via Continuous Measurement

The continuous monitoring of driven dissipative quantum optical systems provides novel strategies for the implementation of quantum metrology. In this context, the relevant figure of merit is the quantum Fisher information of the system's environment, the acceptor of the emitted radiation quanta. Saturation of the corresponding precision limit as defined by the quantum Cramer-Rao bound is typically not achieved by conventional, temporally local continuous measurement schemes such as counting or homodyning. To address the open challenge of efficient retrieval of the environmental quantum Fisher information, we design a novel continuous measurement strategy featuring temporally quasi-local measurement basis as captured by matrix product states. Such measurements can be implemented effectively by injecting the emission field of the system into an auxiliary open system, a `quantum decoder' module, which `decodes' specific input matrix product states into simple product states as its output field, and performing conventional continuous measurement at the output. Our measurement scheme provides a universal method to achieve the quantum Cramer-Rao precision limit for continuous-measurement based (multi-)parameter sensing. As a by-product, we establish an effective method for determining the quantum Fisher information of the emission field of generic open quantum optical systems. We illustrate the power of our approach at the example of sensing unknown system parameters via continuous monitoring the emission field of driven-dissipative emitters coupled to waveguides, and show that it can be robustly implemented under realistic experimental imperfections.Comment: 13 pages, 4 figure

Criticality-enhanced Electromagnetic Field Sensor with Single Trapped Ions

We propose and analyze a driven-dissipative quantum sensor that is continuously monitored close to a dissipative critical point. The sensor relies on the critical open Rabi model with the spin and phonon degrees of freedom of a single trapped ion to achieve criticality-enhanced sensitivity. Effective continuous monitoring of the sensor with nearly unit efficiency is realized via a co-trapped ancilla ion that switches between dark and bright internal states conditioned on a `jump' of the phonon population. We demonstrate that the critical sensor achieves a scaling beyond the standard shot noise limit under realistic conditions and is robust to experimental imperfections.Comment: 5 pages, 4 figure

Capture and sorting of multiple cells by polarization-controlled three-beam interference

For the capture and sorting of multiple cells, a sensitive and highly efficient polarization-controlled three-beam interference set-up has been developed. With the theory of superposition of three beams, simulations on the influence of polarization angle upon the intensity distribution and the laser gradient force change with different polarization angles have been carried out. By controlling the polarization angle of the beams, various intensity distributions and different sizes of dots are obtained. We have experimentally observed multiple optical tweezers and the sorting of cells with different polarization angles, which are in accordance with the theoretical analysis. The experimental results have shown that the polarization angle affects the shapes and feature sizes of the interference patterns and the trapping force

Erratum: >A comparative study of the Si+O2\SiO+O reaction dynamics from quasiclassical trajectory and statistical based methods> [J. Chem. Phys. 128, 174307 (2008)]

Peer Reviewe

Unlocking Heisenberg Sensitivity with Sequential Weak Measurement Preparation

We propose a state preparation protocol based on sequential measurements of a central spin coupled with a spin ensemble, and investigate the usefulness of the generated multi-spin states for quantum enhanced metrology. Our protocol is shown to generate highly entangled spin states, devoid of the necessity for non-linear spin interactions. The metrological sensitivity of the resulting state surpasses the standard quantum limit, reaching the Heisenberg limit under symmetric coupling strength conditions. We also explore asymmetric coupling strengths, identifying specific preparation windows in time for optimal sensitivity. Our findings introduce a novel method for generating large-scale, non-classical, entangled states, enhancing quantum-enhanced metrology within current experimental capabilities.Comment: Figure 1 update

Modification in Structural and Optical Properties of Erbium-doped Zinc Sodium Tellurite Glass: Effect of Bimetallic Nanoparticles

The demand in accomplishing modified structural and optical features of trivalent rare earth (RE) ions doped amorphous media through the incorporation of metallic nanoparticles (NPs) of controlled sizes is ever-increasing for short wavelength solid state lasers development. In this view, we attempt to alter the optical properties of bimetallic NPs and erbium (Er3+) integrated zinc-sodium-tellurite glass. Modifications in structural properties are triggered via precise control of titanium and copper NPs nucleation and growth processes underneath the amorphous matrix. The changes in ligand interactions in the fragile disordered matrix are found to be accountable for the variations in structural and optical properties. A series of glass with composition of (70-x-y)TeO2-20ZnO-9Na2O-1Er2O3-(x)CuO-(y)TiO2 (x = 0.0 and 0.04 mol%; y = 0.0 and 0.1 mol%) are prepared following melt-quenching method and characterized. UV-Vis-NIR spectra displayed seven absorption bands corresponding to the transitions from ground state (4I15/2) to 4F5/2, 4F7/2, 2H11/2, 4S3/2, 4F9/2, 4I9/2 and 4I11/2 excited states of Er3+. FTIR spectra show the presence of symmetric Te-O-Te linkage vibrations and stretching vibrations of Cu-O on monoclinic CuO, Te-O bond of the trigonal bypiramidal unit [TeO4] with non-bridging oxygen symmetrical TeO3 groups and vibrations of water molecule. The presence of bimetallic NPs is confirmed from transmission electron microscopy (TEM) imaging. Our glass composition demonstrating such significant modification in structural and optical properties may be beneficial for the development of plasmonic devices

Molecular excitation in the Interstellar Medium: recent advances in collisional, radiative and chemical processes

We review the different excitation processes in the interstellar mediumComment: Accepted in Chem. Re

Reduced Ordered Binary Decision Diagram with Implied Literals: A New knowledge Compilation Approach

Knowledge compilation is an approach to tackle the computational intractability of general reasoning problems. According to this approach, knowledge bases are converted off-line into a target compilation language which is tractable for on-line querying. Reduced ordered binary decision diagram (ROBDD) is one of the most influential target languages. We generalize ROBDD by associating some implied literals in each node and the new language is called reduced ordered binary decision diagram with implied literals (ROBDD-L). Then we discuss a kind of subsets of ROBDD-L called ROBDD-i with precisely i implied literals (0 \leq i \leq \infty). In particular, ROBDD-0 is isomorphic to ROBDD; ROBDD-\infty requires that each node should be associated by the implied literals as many as possible. We show that ROBDD-i has uniqueness over some specific variables order, and ROBDD-\infty is the most succinct subset in ROBDD-L and can meet most of the querying requirements involved in the knowledge compilation map. Finally, we propose an ROBDD-i compilation algorithm for any i and a ROBDD-\infty compilation algorithm. Based on them, we implement a ROBDD-L package called BDDjLu and then get some conclusions from preliminary experimental results: ROBDD-\infty is obviously smaller than ROBDD for all benchmarks; ROBDD-\infty is smaller than the d-DNNF the benchmarks whose compilation results are relatively small; it seems that it is better to transform ROBDDs-\infty into FBDDs and ROBDDs rather than straight compile the benchmarks.Comment: 18 pages, 13 figure

BASECOL2012: A collisional database repository and web service within the Virtual Atomic and Molecular Data Centre (VAMDC)

The BASECOL2012 database is a repository of collisional data and a web service within the Virtual Atomic and Molecular Data Centre (VAMDC, http://www.vamdc.eu). It contains rate coefficients for the collisional excitation of rotational, ro-vibrational, vibrational, fine, and hyperfine levels of molecules by atoms, molecules, and electrons, as well as fine-structure excitation of some atoms that are relevant to interstellar and circumstellar astrophysical applications. Submissions of new published collisional rate coefficients sets are welcome, and they will be critically evaluated before inclusion in the database. In addition, BASECOL2012 provides spectroscopic data queried dynamically from various spectroscopic databases using the VAMDC technology. These spectroscopic data are conveniently matched to the in-house collisional excitation rate coefficients using the SPECTCOL sofware package (http:// vamdc.eu/software), and the combined sets of data can be downloaded from the BASECOL2012 website. As a partner of the VAMDC, BASECOL2012 is accessible from the general VAMDC portal (http://portal.vamdc.eu) and from user tools such as SPECTCOL