5 research outputs found
Robust Macroscopic Schr\"odinger's Cat on a Nucleus
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
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
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
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In situ amplification of spin echoes within a kinetic inductance parametric amplifier
The use of superconducting microresonators together with quantum-limited Josephson parametric amplifiers has enhanced the sensitivity of pulsed electron spin resonance (ESR) measurements by more than four orders of magnitude. So far, the microwave resonators and amplifiers have been designed as separate components due to the incompatibility of Josephson junction-based devices with magnetic fields. This has produced complex spectrometers and raised technical barriers toward adoption of the technique. Here, we circumvent this issue by coupling an ensemble of spins directly to a weakly nonlinear and magnetic field-resilient superconducting microwave resonator. We perform pulsed ESR measurements with a 1-pL mode volume containing 6 Ă— 107 spins and amplify the resulting signals within the device. When considering only those spins that contribute to the detected signals, we find a sensitivity of [Formula: see text] for a Hahn echo sequence at a temperature of 400 mK. In situ amplification is demonstrated at fields up to 254 mT, highlighting the technique's potential for application under conventional ESR operating conditions
Navigating the 16-dimensional Hilbert space of a high-spin donor qudit with electric and magnetic fields
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