Detecting itinerant single microwave photons

Single photon detectors are fundamental tools of investigation in quantum optics and play a central role in measurement theory and quantum informatics. Photodetectors based on different technologies exist at optical frequencies and much effort is currently being spent on pushing their efficiencies to meet the demands coming from the quantum computing and quantum communication proposals. In the microwave regime however, a single photon detector has remained elusive although several theoretical proposals have been put forth. In this article, we review these recent proposals, especially focusing on non-destructive detectors of propagating microwave photons. These detection schemes using superconducting artificial atoms can reach detection efficiencies of 90\% with existing technologies and are ripe for experimental investigations.Comment: 11 pages, 8 figure

The role of matrix metalloproteinases in leukocyte migration and collagen degradation in tuberculosis

Tuberculosis (TB) causes disease worldwide and multi-drug resistance is rising. Matrix metalloproteinases (MMPs) cause immunopathological lung matrix destruction, which results in transmission, morbidity and mortality. Collagen is the primary structural fibril of the lung and I primarily studied two collagenases: secreted MMP-8, and membrane bound MMP-14, and also the stromelysin MMP-10, which activates not only MMP-8 but another collagenase MMP-1. Human monocyte and macrophages were stimulated with Mtb H37Rv, BCG, ESAT-6 peptides or Conditioned Media from Mtb infected monocytes (CoMTb). MMP concentrations were measured by Luminex bead array and ELISA. Gene expression was quantified by RT-PCR. Immunohistochemistry was performed on biopsies. Flow cytometry quantified MMP-14 expression. Fluorescent microscopy detected MMP-14 and monocyte driven fluorescent collagen degradation. Monocyte migration was measured by the agarose spot assay. MMP-8 was increased in the plasma in TB compared to both respiratory symptomatics and controls (both p<0.001). MMP-10 was increased in the respiratory secretions of patients with TB compared to controls (p<0.05). Mtb drove up to a 31.5 fold increase in MMP-10 secretion from macrophages (both p<0.001). Mtb caused 3.5 fold more MMP-10 secretion from macrophages than BCG (p<0.001) and a specific peptide from ESAT-6 drove MMP-10 secretion from macrophages. In induced sputum, MMP-14 mRNA was increased 3.3-fold in TB compared to controls and positively correlated with infiltration on chest radiograph (both p<0.05). Macrophages of TB granulomas in biopsies stained strongly positive for MMP-14. Mtb increased monocyte MMP-14 surface expression 31.7-fold (p<0.05) and CoMTb 17.5-fold (p<0.01). Mtb infected monocytes degraded collagen, with co-localised MMP-14 surface expression. Monocytes migrated to the edge of CoMTb impregnated agarose drops, expressing MMP-14 on migration. Inhibition of MMP-14 activity with a neutralising antibody, decreased Mtb driven collagen degradation by 73% (p< 0.001) and CoMTb driven monocyte migration by 44% (p<0.001). These data shows that, MMP-1, -8, -10 and -14 cause immunopathology and regulate leukocyte migration in TB.Open Acces

Quantum non-demolition detection of propagating microwave photons

Typical photon counters involve absorption of photons to generate electric signals, thus basically destroying the information carried by the photon. This is all the more disastrous if the photon is used as a quantum information carrier, such as a part of an entangled pair. Quantum non-demolition (QND) measurements are de- signed to overcome this limitation. Such a non-destructive photon detection would play a key role in quantum networks where photons can be used as “flying” qubits. In this thesis, using circuit QED we investigate if QND detection of a prop- agating microwave photon is possible. The system considered consists of a three level artificial atom (transmon) interacting with signal and probe fields. The fields are in the microwave regime with their frequencies on par with the energy levels of the transmon. The interaction of these two fields with the artificial atom, imparts a phase change on the probe field via the cross-Kerr effect. By measuring this phase change, we indirectly infer the presence of the signal. In this thesis, we investigate if it is possible to achieve a single photon detection, at first using a single transmon and then using multiple transmons. We find that, while single photon detection is not possible with a single transmon, it is indeed possible with multiple transmons under certain conditions. We also find that with multiple transmons, we can have a large phase change in the probe, which might be desirable in other applications

Storage and on-demand release of microwaves using superconducting resonators with tunable coupling

We present a system which allows to tune the coupling between a superconducting resonator and a transmission line. This storage resonator is addressed through a second, coupling resonator, which is frequency-tunable and controlled by a magnetic flux applied to a superconducting quantum interference device (SQUID). We experimentally demonstrate that the lifetime of the storage resonator can be tuned by more than three orders of magnitude. A field can be stored for 18 {\mu}s when the coupling resonator is tuned off resonance and it can be released in 14 ns when the coupling resonator is tuned on resonance. The device allows capture, storage, and on-demand release of microwaves at a tunable rate.Comment: 5 pages, 3 figure

Rearing of post-larvae of Penaeus monodon in nursery pond-an experimental study

In the present experiment, Poetlarvae of Penaeus monodon received from M/s Hindustan Lever Hatchery, Muttukkadu were reared in a nursery pond at porto Novo. In a span of one month, they were reared to the stockable size of 30 to 48 mm (average size 38 mm) from an initial size of 8 to 12 mm ^average size 10 mm). Pond was suitably prepared after the application of cowdung. Coconut end palm leaves were fixed at the sides of the pond to avoid the direct heat of the sun and evoporation. Clam meat [Meretrix sp.) was used as the supplementary feed at 100% body weight- Hydrographical conditions of the pond waters in relation to length and weight (growth) have been discussed. About 98% recovery was achieved

Resonant and off-resonant microwave signal manipulation in coupled superconducting resonators

We present an experimental demonstration as well as a theoretical model of an integrated circuit designed for the manipulation of a microwave field down to the single-photon level. The device is made of a superconducting resonator coupled to a transmission line via a second frequency-tunable resonator. The tunable resonator can be used as a tunable coupler between the fixed resonator and the transmission line. Moreover, the manipulation of the microwave field between the two resonators is possible. In particular, we demonstrate the swapping of the field from one resonator to the other by pulsing the frequency detuning between the two resonators. The behavior of the system, which determines how the device can be operated, is analyzed as a function of one key parameter of the system, the damping ratio of the coupled resonators. We show a good agreement between experiments and simulations, realized by solving a set of coupled differential equations.Comment: 10 pages, 6 figure

Simple, robust and on-demand generation of single and correlated photons

We propose two different setups to generate single photons on demand using an atom in front of a mirror, along with either a beam-splitter or a tunable coupling. We show that photon generation efficiency ~99% is straightforward to achieve. The proposed schemes are simple and easily tunable in frequency. The operation is relatively insensitive to dephasing and can be easily extended to generate correlated pairs of photons. They can also in principle be used to generate any photonic qubit of the form $\mu |0 \rangle + \nu |1\rangle$ in arbitrary wave-packets, making them very attractive for quantum communication applications.Comment: 10 pages, Added appendi