155 research outputs found

    Asymptotic state transformations of continuous variable resources

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    We prove that strongly superadditive monotones can be used to bound asymptotic state transformation rates in continuous variable resource theories. This removes the need for asymptotic continuity, which is typically lost in infinite-dimensional settings. We consider three applications, to the resource theories of (I) optical nonclassicality, (II) entanglement, and (III) quantum thermodynamics. In cases (II) and (III), the employed monotones are the squashed entanglement and the free energy, respectively. For case (I), we consider the measured relative entropy of nonclassicality and prove it to be strongly superadditive. Our technique then yields computable upper bounds on asymptotic transformation rates including those achievable under linear optical elements. We conclude by applying our findings to the problem of cat state manipulation.Comment: 7+34 pages, 1+5 figure

    Experimental quantification of coherence of a tunable quantum detector

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    Quantum coherence is a fundamental resource that quantum technologies exploit to achieve performance beyond that of classical devices. A necessary prerequisite to achieve this advantage is the ability of measurement devices to detect coherence from the measurement statistics. Based on a recently developed resource theory of quantum operations, here we quantify experimentally the ability of a typical quantum-optical detector, the weak-field homodyne detector, to detect coherence. We derive an improved algorithm for quantum detector tomography and apply it to reconstruct the positive-operator-valued measures (POVMs) of the detector in different configurations. The reconstructed POVMs are then employed to evaluate how well the detector can detect coherence using two computable measures. As the first experimental investigation of quantum measurements from a resource theoretical perspective, our work sheds new light on the rigorous evaluation of the performance of a quantum measurement apparatus

    Threshold Energy Switching and Its Application to Wireless Sensing

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    ABSTRACT A solid state threshold energy switching device based on a relaxation oscillator is discussed in the context of a self energizing wireless pressure sensor. The study is an integral part of the design of a wireless pressure sensor for in-situ injection molding machine cavity pressure measurement and real time process control. The pressure information is measured using a piezoelectric stack and converted to a train of ultrasonic pulses, using the oscillator based threshold switching device, to a receiver outside of the mold. In this paper the threshold switching device is developed, simulated using a circuit simulation program, and validated experimentally. Its properties are discussed with reference to pressure measurement and acoustic signal transmission. INTRODUCTION It has been shown that direct cavity pressure and temperature measurement, more than any indirect method, is related to final part qualit
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