A "Single-Photon" Transistor in Circuit Quantum Electrodynamics

We introduce a circuit quantum electrodynamical setup for a "single-photon" transistor. In our approach photons propagate in two open transmission lines that are coupled via two interacting transmon qubits. The interaction is such that no photons are exchanged between the two transmission lines but a single photon in one line can completely block respectively enable the propagation of photons in the other line. High on-off ratios can be achieved for feasible experimental parameters. Our approach is inherently scalable as all photon pulses can have the same pulse shape and carrier frequency such that output signals of one transistor can be input signals for a consecutive transistor.Comment: Analysis of pure dephasing, time delays between pulses and gain added. Word "quantum" dropped from title, to appear in Phys. Rev. Let

Bounded Privacy: Formalising the Trade-Off Between Privacy and Quality of Service

Many services and applications require users to provide a certain amount of information about themselves in order to receive an acceptable quality of service (QoS). Exemplary areas of use are location based services like route planning or the reporting of security incidents for critical infrastructure. Users putting emphasis on their privacy, for example through anonymization, therefore usually suffer from a loss of QoS. Some services however, may not even be feasible above a certain threshold of anonymization, resulting in unacceptable service quality. Hence, there need to be restrictions on the applied level of anonymization. To prevent the QoS from dropping below an unacceptable threshold, we introduce the concept of Bounded Privacy, a generic model to describe situations in which the achievable level of privacy is bounded by its relation to the service quality. We furthermore propose an approach to derive the optimal level of privacy for both discrete and continuous data

Tunable coupler to fully decouple superconducting qubits

Enhancing the capabilities of superconducting quantum hardware, requires higher gate fidelities and lower crosstalk, particularly in larger scale devices, in which qubits are coupled to multiple neighbors. Progress towards both of these objectives would highly benefit from the ability to fully control all interactions between pairs of qubits. Here we propose a new coupler model that allows to fully decouple dispersively detuned Transmon qubits from each other, i.e. ZZ-crosstalk is completely suppressed while maintaining a maximal localization of the qubits' computational basis states. We further reason that, for a dispersively detuned Transmon system, this can only be the case if the anharmonicity of the coupler is positive at the idling point. A simulation of a 40ns CZ-gate for a lumped element model suggests that achievable process infidelity can be pushed below the limit imposed by state-of-the-art coherence times of Transmon qubits. On the other hand, idle gates between qubits are no longer limited by parasitic interactions. We show that our scheme can be applied to large integrated qubit grids, where it allows to fully isolate a pair of qubits, that undergoes a gate operation, from the rest of the chip while simultaneously pushing the fidelity of gates to the limit set by the coherence time of the individual qubits.Comment: 6 pages, 4 figure

Ultrasonication and the quality of human milk: variation of power and time of exposure

Donor human milk is pasteurized to prevent the potential risk of the transmission of pathogens to preterm infants. Currently, Holder pasteurization (human milk held at 62·5°C for 30 min) is used in most human milk banks, but has the disadvantage that it results in excessive inactivation of important bioactive components. Power-ultrasound (20-100 kHz) is an emerging technology for the preservation of foods and could be an alternative method for the treatment of human milk. The aim of this study was to investigate the effect of different ultrasound settings on the elimination of Escherichia coli and the retention of bile salt stimulated lipase (BSSL) activity. Ultrasonication with a constant power decreased Esch. coli viability exponentially over time until the processing temperature increased to sub-pasteurization level to between 51·4 and 58·5°C, then a log10 1·3 decrease was observed (P<0·05). BSSL activity decreased to 91% until a temperature of 51·4°C and then it decreased to 8% between 51·4 and 64·9°C. Ultrasonication with a constant energy and various power and exposure times showed the highest temperature (53·7°C) when treated with the longest exposure time and lowest ultrasound-power (276 s at 3·62 W) compared with 37·6°C for 39 s at 25·64 W. The findings predict that the viability of Esch. coli could be reduced by log10 5 with a minimal loss of activity of BSSL by applying 13·8 kJ of energy in 12 ml of human milk using high ultrasound power over a short exposure time to ensure that the temperature remains below the critical level for protein denaturation. Alternatively, the use of lower power settings such as the 26 W used in the present studies would require a cooling system to ensure the human milk BSSL was protected against temperature denaturatio

Experimental Investigation of the Spread of Airborne CFU in a Research-OR under Different Air Flow Regimes using Tracer Particles

Aim of this experimental study is to compare different types of ventilation in operating rooms (OR) regarding the highest possible patient protection against airborne germs based on particle counting. Tracer particles with the size of the airborne colony-forming units (CFU) occurring in OR shall be generated to derive representative statements about the removal of germs. In addition, they origin from aerosol generators mounted on heated person simulators to obtain a realistic dispersion of the contamination. It can be shown that the aerosol generators designed produce particles in the relevant size classes of the airborne germs emitted by OR personnel.publishedVersio

Determinants of older peoples's preferences for dispensing doctors

Objectives: Dispensing doctors (DDs) are a central part of the medication supply in Austria. Nevertheless, they are controversial and research pays little attention to perspectives of user-groups, especially older people. Therefore, this article deals with determinants of older people’s approval of dispensing doctors.Methods: For this purpose, data from a telephone survey with people over 60 years in Lower Austria are used and evaluated by means of a logit model.Results: The results show that accessibility of medicines is a major reason for the preference of DDs. Key factors are availability of a pharmacy in close proximity (OR: 0.44), independent use of a car (OR: 1.54) and individual mobility due to health reasons (OR: 1.14).Discussion: DDs are important for older people in terms of a spatially close drug supply. A pharmacy at the place of residence only outweighs the preference for DDs if it is actually accessible for older people (taking low travel costs into account).Conclusions: The aim must be to improve access to medicines in all communities where there is no pharmacy within a reasonable distance for people with health problems or those with restricted mobility

Visualizing the Local Optical Response of Semiconducting Carbon Nanotubes to DNA-Wrapping

We studied the local optical response of semiconducting single-walled carbon nanotubes to wrapping by DNA segments using high resolution tip-enhanced near-field microscopy. Photoluminescence (PL) near-field images of single nanotubes reveal large DNA-wrapping-induced red shifts of the exciton energy that are two times higher than indicated by spatially averaging confocal microscopy. Near-field PL spectra taken along nanotubes feature two distinct PL bands resulting from DNA-wrapped and unwrapped nanotube segments. The transition between the two energy levels occurs on a length scale smaller than our spatial resolution of about 15 nm

An inconspicuous, conspicuous new species of Asian pipesnake, genus Cylindrophis (Reptilia: Squamata: Cylindrophiidae), from the south coast of Jawa Tengah, Java, Indonesia, and an overview of the tangled taxonomic history of C. ruffus (Laurenti, 1768)

We describe a new species of Cylindrophis currently known only from Grabag, Purworejo Regency, Jawa Tengah Province (Central Java), Java, Indonesia. Cylindrophis subocularis sp. nov. can be distinguished from all congeners by the presence of a single, eponymous subocular scale between the 3rd and 4th or 4th and 5th supralabial, preventing contact between the 4th or 5th supralabial and the orbit, and by having the prefrontal in narrow contact with or separated from the orbit. We preface our description with a detailed account of the tangled taxonomic history of the similar and putatively wide-ranging species C. ruffus, which leads us to (1) remove the name Scytale scheuchzeri from the synonymy of C. ruffus, (2) list the taxon C. rufa var. javanica as species inquirenda, and (3) synonymize C. mirzae with C. ruffus. We provide additional evidence to confirm that the type locality of C. ruffus is Java. Cylindrophis subocularis sp. nov. is the second species of Asian pipesnake from Java

Sensitivity of resonant tunneling diode photodetectors

The authors are grateful for financial support by the BMBF via national project EIPHRIK (FKZ: 13N10710) and the European Union (FPVII (2007-2013) under Grant Agreement No. 318287 LANDAUER).We have studied the sensitivity of AlGaAs/GaAs double barrier resonant tunneling diode photodetectors with an integrated GaInNAs absorption layer for light sensing at the telecommunication wavelength of λ=1.3 µm for illumination powers from pico to micro Watts. The sensitivity decreases nonlinearly with power. An illumination power increase of seven orders of magnitude leads to a reduction of the photocurrent sensitivity from SI =5.82 × 103 A/W to 3.2 A/W. We attribute the nonlinear sensitivity-power dependence to an altered local electrostatic potential due to hole-accumulation that on the one hand tunes the tunneling current, but on the other hand affects the lifetime of photogenerated holes. In particular, the lifetime decreases exponentially with increasing hole-population. The lifetime reduction results from an enhanced electrical field, a rise of the quasi-Fermi level and an increased energy splitting within the triangular potential well. The non-constant sensitivity is a direct result of the non-constant lifetime. Based on these findings, we provide an expression that allows to calculate the sensitivity as a function of illumination power and bias voltage, show a way to model the time-resolved photocurrent, and determine the critical power up to which the resonant tunneling diode photosensor sensitivity can be assumed constant.PostprintPeer reviewe

Aerosol emission of adolescents voices during speaking, singing and shouting

Since the outbreak of the COVID-19 pandemic, singing activities for children and young people have been strictly regulated with far-reaching consequences for music education in schools and ensemble and choir singing in some places. This is also due to the fact, that there has been no reliable data available on aerosol emissions from adolescents speaking, singing, and shouting. By utilizing a laser particle counter in cleanroom conditions we show, that adolescents emit fewer aerosol particles during singing than what has been known so far for adults. In our data, the emission rates ranged from 16 P/s to 267 P/s for speaking, 141 P/s to 1240 P/s for singing, and 683 P/s to 4332 P/s for shouting. The data advocate an adaptation of existing risk management strategies and rules of conduct for groups of singing adolescents, like gatherings in an educational context, e.g. singing lessons or choir rehearsals