INVITATION
to a TALK by
Andrea Morello
Scientia Professor
School of Electrical Engineering and Telecommunications,
UNSW Sydney, Australia
Schrödinger cat in a silicon box: quantum information and quantum foundations
Wednesday, October 1st 2025, 14:00 h
Location: Christian-Doppler Lecture Hall, 3rd floor, Boltzmanngasse 5
Hosted by: Markus Arndt
Abstract:
I will present recent experiments, and exciting new directions, for the use of high-spin nuclei in silicon for quantum information, quantum foundations, and spin-mechanics entanglement. Nuclear spins in silicon are among the most coherent quantum objects to be found in the solid state. They have infinite relaxation time, and second-scale coherence time [1]. By using the I=7/2, 8-dimensional nucleus of antimony [2], we have prepared a nuclear Schrödinger cat within a functional nanoelectronic device [3].
We then used this and other nonclassical states to perform a curious experiment, where the quantumness of the state is certified by monitoring its uniform precession, in seeming contradiction with Ehrenfest's theorem [4].
The nuclear Schrödinger cat can be used to encode a cat-qubit similar to the bosonic encodings used in microwave cavities, but with atomic size, and even more extreme noise bias. We have experimentally demonstrated the fault-tolerant operation of an error-corrected, cat-encoded qubit in silicon, and shown that its adoption reduces the error rates of both quantum memory and quantum logic operations.
High-spin nuclei possess a quadrupole moment that couples them to lattice strain [5]. I will discuss plans to entangle a single nuclear spin with a MHz-range mechanical oscillator, and perspectives to scale up the mass of the oscillator to test gravitational collapse models.
[1] J. Muhonen et al., Nature Nanotechnology 9, 986 (2014)
[2] S. Asaad, V. Mourik et al., Nature 579, 205 (2020)
[3] X. Yu et al., Nature Physics 21, 362 (2025)
[4] A. Vaartjes et al., Newton 1, 100017 (2025)
[5] L. O'Neill et al., Applied Physics Letters 119, 174001 (2021)
