Thursday, October 3, 2024

Quantum Always


Physicists demonstrate first metro-area quantum computer network in Boston
May 2024, phys.org

Quantums now in the US, the last one was in China:

Using existing Boston-area telecommunication fiber, their photons were deployed over a roughly 22-mile loop through Cambridge, Somerville, Watertown, and Boston, with quantum computers at the nodes.

via Harvard: Mikhail Lukin, Entanglement of nanophotonic quantum memory nodes in a telecom network, Nature (2024). DOI: 10.1038/s41586-024-07252-z.



A place to study qubits shielded from the effects of cosmic rays
Jun 2024, phys.org

QUIET and LOUD - a pair of quantum sensors, one above ground and one under. 

via Fermi National Accelerator Laboratory and the National Quantum Initiative


A framework to construct quantum spherical codes
Jun 2024, phys.org

Photonic quantum coding theory:

All quantum codes require the superposition of something, and Albert and his colleagues realized that it made sense to superimpose well-separated points on a sphere. Their framework builds on a previously proposed method to map electromagnetic signals of any frequency into points on a sphere.

"There is an old and very general technique by the founder of information theory, Claude Shannon, that maps an arbitrary electromagnetic signal of fixed amplitude but of any frequency into a point on the sphere," Albert explained. "This means that efficiently sending classical information using light boils down to packing as many points on the sphere as possible while making sure that noise does not cause them to overlap."

via NIST and University of Maryland: Shubham P. Jain et al, Quantum spherical codes, Nature Physics (2024). DOI: 10.1038/s41567-024-02496-y


Pseudomagic quantum states: A path to quantum supremacy
Jun 2024, phys.org

Don't even bother to understand, just know magic states: 

A stabilizer state is a type of quantum state that can be efficiently simulated on a classical computer, and nonstabilizerness or magic refers to a measure of the non-classical resources possessed by a quantum state.

Pseudomagic quantum states appear to have the properties of nonstabilizer states (complexity and non-classical operations) but are computationally indistinguishable from random quantum states, at least to an observer with limited computational resources.

via Harvard University and Freie Universität Berlin: Andi Gu et al, Pseudomagic Quantum States, Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.132.210602.


Quantum annealer improves understanding of quantum many-body systems
Jun 2024, phys.org 

They used a quantum annealer to model a real-life quantum material and showed that the quantum annealer can directly mirror the microscopic interactions of electrons in the material.

In this study, the scientists investigated the quantum material 1T-TaS2.

"We have placed the system in a non-equilibrium state and observed how the electrons in the solid-state lattice rearrange themselves after a non-equilibrium phase transition, both experimentally and through simulations."

The scientists demonstrated that the quantum annealer's qubit interconnections can directly mirror the microscopic interactions between electrons in a quantum material. Only one single parameter in the quantum annealer must be modified. The outcome aligns closely with the experimental findings.

via Forschungszentrum Jülich Supercomputing Center and D-Wave: Jaka Vodeb et al, Non-equilibrium quantum domain reconfiguration dynamics in a two-dimensional electronic crystal and a quantum annealer, Nature Communications (2024). DOI: 10.1038/s41467-024-49179-z

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