Threshold detection statistics of bosonic states

In quantum photonics, threshold detectors, distinguishing between vacuum and one or more photons, such as superconducting nanowires and avalanche photodiodes, are routinely used to measure Fock and Gaussian states of light. Despite being the standard measurement scheme, there is no general closed form expression for measurement probabilities with threshold detectors, unless accepting coarse approximations or combinatorially scaling summations. Here, we present new matrix functions to fill this gap. We develop the Bristolian and the loop Torontonian functions for threshold detection of Fock and displaced Gaussian states, respectively, and connect them to each other and to existing matrix functions. By providing a unified picture of bosonic statistics for most quantum states of light, we provide novel tools for the design and analysis of photonic quantum technologies.Comment: 14 pages, 2 figures, 1 tabl

Scheme for Universal High-Dimensional Quantum Computation with Linear Optics

Photons are natural carriers of high-dimensional quantum information, and, in principle, can benefit from higher quantum information capacity and noise-resilience. However, schemes to generate the resources required for high-dimensional quantum computing have so far been lacking in linear optics. Here, we show how to generate GHZ states in arbitrary dimensions and numbers of photons using linear optical circuits described by Fourier transform matrices. Combining our results with recent schemes for qudit Bell measurements, we show that universal linear optical quantum computing can be performed in arbitrary dimensions

A proposal for practical multidimensional quantum networks

A Quantum Internet, i.e., a global interconnection of quantum devices, is the long term goal of quantum communications, and has so far been based on two-dimensional systems (qubits). Recent years have seen a significant development of high-dimensional quantum systems (qudits). While qudits present higher photon information efficiency and robustness to noise, their use in quantum networks present experimental challenges due to the impractical resources required in high-dimensional quantum repeaters. Here, we show that such challenges can be met via the use of standard quantum optical resources, such as weak coherent states or weak squeezed states, and linear optics. We report a concrete design and simulations of an entanglement swapping scheme for three and four dimensional systems, showing how the network parameters can be tuned to optimize secret key rates and analysing the enhanced noise robustness at different dimensions. Our work significantly simplifies the implementation of high-dimensional quantum networks, fostering their development with current technology.Comment: 7 pages, 4 figure

Epidemiological and birth weight characteristics of triplets: a study from the Dutch twin register

registered in the Dutch Twin Register, several details such as birth weight, gestational age, zygosity, and etiology were assessed by questionnaire, which was tilled out by the mother. For 33 triplet sets, zygosity was also assessed by blood typing. Maternal smoking during pregnancy was also noted. Results show a very strong increase in number of tripletscaused by artificial fertility enhancing techniques and consequently a shift in the relative contribution of zygosity types to the total number of triplets. Birth weight is predominantly intluenced by gestational age. Other effects on birth weight are controlled for possible confounding with gestational age. First born triplets weigh more than later born triplets; boys weigh more than girls; nearly 25 % of all individual triplets weigh less than 1500 g, i.e. belong to the category very low birth weight (VLBW); regular maternal smoking produces a 14 % birth weight reduction; ovulation induction seems to decrease the sex ratio, i.e. hormonal treatment with ovulation inducing substances increases the probability of female offspring. Triplet; Birth weight; Multiple birth epidemiology; In vitro fertilization; Ovulation-induction; Sex; Maternal smokin

Pure-state certification by undoing Hamiltonian evolution leading to local thermalization

In a quantum-photonic experiment with an integrated quantum photonics network, we observe a quantum state locally evolve towards a thermal state. By undoing the evolution with the inverse network, we recover the input pure state