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Quantum simulations are becoming an essential tool for studying complex phenomena, e.g. quantum topology, quantum information transfer and relativistic wave equations, beyond the limitations of analytical computations and experimental observations. To date, the primary resources used in proof-of-principle experiments are collections of qubits, coherent states or multiple single-particle Fock states. Here we show a quantum simulation performed using genuine higher-order Fock states, with two or more indistinguishable particles occupying the same bosonic mode. This was implemented by interfering pairs of Fock states with up to five photons on an interferometer, and measuring the output states with photon-number-resolving detectors. Already this resource-efficient demonstration reveals topological matter, simulates non-linear systems and elucidates a perfect quantum transfer mechanism which can be used to transport Majorana fermions.

Quantum simulations are becoming an essential tool for studying complex phenomena, e.g. quantum topology, quantum information transfer, and relativistic wave equations, beyond the limitations of analytical computations and experimental observations. To date, the primary resources used in proof-of-principle experiments are collections of qubits, coherent states or multiple single-particle Fock states. Here we show the first quantum simulation performed using genuine higher-order Fock states, with two or more indistinguishable particles occupying the same bosonic mode. This was implemented by interfering pairs of Fock states with up to five photons on an interferometer, and measuring the output states with photon-number-resolving detectors. Already this resource-efficient demonstration reveals new topological matter, simulates non-linear systems and elucidates a perfect quantum transfer mechanism which can be used to transport Majorana fermions.

Variable measurement operators enable the optimization of strategies for testing quantum properties and the preparation of a range of quantum states. Here, we experimentally implement a weak-field homodyne detector that can continuously tune between measuring photon numbers and field quadratures. We combine a quantum signal with a coherent state on a balanced beam splitter and detect light at both output ports using photon-number-resolving transition edge sensors. We observe that the discrete difference statistics converge to the quadrature distribution of the signal as we increase the coherent state amplitude. Moreover, in a proof-of-principle demonstration of state engineering, we show the ability to control the photon-number distribution of a state that is heralded using our weak-field homodyne detector.

It is an open question how fast information processing can be performed and whether quantum effects can speed up the best existing solutions. Signal extraction, analysis and compression in diagnostics, astronomy, chemistry and broadcasting builds on the discrete Fourier transform. It is implemented with the Fast Fourier Transform (FFT) algorithm that assumes a periodic input of specific lengths, which rarely holds true. A less-known transform, the Kravchuk-Fourier (KT), allows one to operate on finite strings of arbitrary length. It is of high demand in digital image processing and computer vision, but features a prohibitive runtime. Here, we report a one-step computation of a fractional quantum KT. A quantum \\(d\\)-nary (qudit) architecture we use comprises only one gate and offers processing time independent of the input size. The gate may employ a multiphoton Hong-Ou-Mandel effect. Existing quantum technologies may scale it up towards diverse applications.

In a recent contribution, we introduced and applied a detector-independent method to uncover nonclassicality. Here, we extend those techniques and give more details on the performed analysis. We derive a general theory of the positive-operator-valued measure that describes multiplexing layouts with arbitrary detectors. From the resulting quantum version of a multinomial statistics, we infer nonclassicality probes based on a matrix of normally ordered moments. We discuss these criteria and apply the theory to our data which are measured with superconducting transition-edge sensors. Our experiment produces heralded multi-photon states from a parametric down-conversion light source. We show that the known notions of sub-Poisson and sub-binomial light can be deduced from our general approach, and we establish the concept of sub-multinomial light, which is shown to outperform the former two concepts of nonclassicality for our data.

We introduce a method for the verification of nonclassical light which is independent of the complex interaction between the generated light and the material of the detectors. This is accomplished by means of a multiplexing arrangement. Its theoretical description yields that the coincidence statistics of this measurement layout is a mixture of multinomial distributions for any classical light field and any type of detector. This allows us to formulate bounds on the statistical properties of classical states. We apply our directly accessible method to heralded multiphoton states which are detected with a single multiplexing step only and two detectors, which are in our work superconducting transition-edge sensors. The nonclassicality of the generated light is verified and characterized through the violation of the classical bounds without the need for characterizing the used detectors.

An all-fiber 1.48 µm generator based on a LD-pumped Yb-doped double-clad laser and cascaded Raman wavelength converter has been developed. Second-order Raman Stokes radiation was generated in a phosphosilicate-fiber resonator formed by two pairs of Bragg gratings. The Yb-doped double-clad fiber laser was pumped by seven laser diodes combined via a low-loss fused fiber coupler and provided 4.4 W at 1.06 µm at the input of the Raman converter. A slope efficiency of the Raman converter of 40% with respect to the power emitted by the double-clad Yb laser has been achieved. We obtained an output power of 1.5 W with a total optical-to-optical efficiency of 21%. It was found that four-wave mixing, initiated in the fiber by the high-intensity light, results in spectral broadening of the 1.48 µm radiation and leaking of the first-Stokes radiation from the resonator formed by the 1.24 µm Bragg gratings, thus reducing the efficiency of the first-to-second-Stokes conversion.PACS No.: 42.55Wd

An all-fiber 1.48 (mu)m generator based on a LD-pumped Yb-doped double-clad laser and cascaded Raman wavelength converter has been developed. Second-order Raman Stokes radiation was generated ina phosphosilicate-fiber resonator formed by two pairs of Bragg gratings.

An all-fiber 1.48-micron generator based on an LD-pumped Yb-doped double-clad laser and cascaded Raman wavelength converter has been developed. Second-order Raman Stokes radiation was generated in a phosphosilicate-fiber resonator formed by two pairs of Bragg gratings. The Yb-doped double-clad fiber laser was pumped by seven laser diodes combined via a low-loss fused fiber coupler, and provided 4.4 W at 1.06 micron at the input of the Raman converter. A slope efficiency of the Raman converter of 40 percent with respect to the power emitted by the double-clad Yb laser has been achieved. We obtained an output power of 1.5 W with a total optical-to-optical efficiency of 21 percent. It was found that four-wave mixing, initiated in the fiber by the high-intensity light, results in spectral broadening of the 1.48-micron radiation and leaking of the first-Stokes radiation from the resonator formed by the 1.24-micron Bragg gratings, thus reducing the efficiency of the first-to-second-Stokes conversion. (Author)

An all-fiber 1.48 km generator based on a LD-pumped Yb-doped double-clad laser and cascaded Raman wavelength converter has been developed. Second-order Raman Stokes radiation was generated in a phosphosilicate-fiber resonator formed by two pairs of Bragg gratings. The Yb-doped double-clad fiber laser was pumped by seven laser diodes combined via a low-loss fused fiber coupler and provided 4.4 W at 1.06 km at the input of the Raman converter. A slope efficiency of the Raman converter of 40% with respect to the power emitted by the double-clad Yb laser has been achieved. We obtained an output power of 1.5 W with a total optical-to-optical efficiency of 21%. It was found that four-wave mixing, initiated in the fiber by the high-intensity light, results in spectral broadening of the 1.48 km radiation and leaking of the first-Stokes radiation from the resonator formed by the 1.24 km Bragg gratings, thus reducing the efficiency of the first-to-second-Stokes conversion.