5 research outputs found

    Robust Macroscopic Schr\"odinger's Cat on a Nucleus

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    We propose an experimentally feasible scheme to create large Schr\"odinger cat states on a high-spin nucleus of a donor atom embedded in a solid-state system. The resulting cat state is robust against decoherence, macroscopic because its size scales linearly with nuclear spin, and tiny -- at the femtometer scale. Our quantum-control scheme utilizes one-axis twisting caused by a non-linear quadrupole interaction and phase-modulated multi-tone radio-frequency pulses for universal high-dimensional rotations. We achieve fast generation and detection for yielding robust cat states and observing rapid collapse-and-revivals -- two orders of magnitude faster than the dephasing timescale.Comment: 7 pages, 4 figure

    Strong Microwave Squeezing Above 1 Tesla and 1 Kelvin

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    Squeezed states of light have been used extensively to increase the precision of measurements, from the detection of gravitational waves to the search for dark matter. In the optical domain, high levels of vacuum noise squeezing are possible due to the availability of low loss optical components and high-performance squeezers. At microwave frequencies, however, limitations of the squeezing devices and the high insertion loss of microwave components makes squeezing vacuum noise an exceptionally difficult task. Here we demonstrate a new record for the direct measurement of microwave squeezing. We use an ultra low loss setup and weakly-nonlinear kinetic inductance parametric amplifiers to squeeze microwave noise 7.8(2) dB below the vacuum level. The amplifiers exhibit a resilience to magnetic fields and permit the demonstration of record squeezing levels inside fields of up to 2 T. Finally, we exploit the high critical temperature of our amplifiers to squeeze a warm thermal environment, achieving vacuum level noise at a temperature of 1.8 K. These results enable experiments that combine squeezing with magnetic fields and permit quantum-limited microwave measurements at elevated temperatures, significantly reducing the complexity and cost of the cryogenic systems required for such experiments.Comment: Main text: 9 pages, 4 figures. Supplementary information: 21 pages, 17 figure

    Navigating the 16-dimensional Hilbert space of a high-spin donor qudit with electric and magnetic fields

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    Efficient scaling and flexible control are key aspects of useful quantum computing hardware. Spins in semiconductors combine quantum information processing with electrons, holes or nuclei, control with electric or magnetic fields, and scalable coupling via exchange or dipole interaction. However, accessing large Hilbert space dimensions has remained challenging, due to the short-distance nature of the interactions. Here, we present an atom-based semiconductor platform where a 16-dimensional Hilbert space is built by the combined electron-nuclear states of a single antimony donor in silicon. We demonstrate the ability to navigate this large Hilbert space using both electric and magnetic fields, with gate fidelity exceeding 99.8% on the nuclear spin, and unveil fine details of the system Hamiltonian and its susceptibility to control and noise fields. These results establish high-spin donors as a rich platform for practical quantum information and to explore quantum foundations.Comment: 31 pages and 19 figures including Supplementary Material

    Navigating the 16-dimensional Hilbert space of a high-spin donor qudit with electric and magnetic fields

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    Abstract Efficient scaling and flexible control are key aspects of useful quantum computing hardware. Spins in semiconductors combine quantum information processing with electrons, holes or nuclei, control with electric or magnetic fields, and scalable coupling via exchange or dipole interaction. However, accessing large Hilbert space dimensions has remained challenging, due to the short-distance nature of the interactions. Here, we present an atom-based semiconductor platform where a 16-dimensional Hilbert space is built by the combined electron-nuclear states of a single antimony donor in silicon. We demonstrate the ability to navigate this large Hilbert space using both electric and magnetic fields, with gate fidelity exceeding 99.8% on the nuclear spin, and unveil fine details of the system Hamiltonian and its susceptibility to control and noise fields. These results establish high-spin donors as a rich platform for practical quantum information and to explore quantum foundations
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