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What’s going on inside quantum computers? New method simplifies process tomography

Quantum computers work by applying quantum operations, such as quantum gates, to delicate quantum states. Ideally, quantum computers can solve complex equations at staggeringly fast speeds that vastly outpace regular computers. In real hardware, the operations of quantum computers often deviate from the ideal behavior because of device imperfections and unwanted noise from the environment. To build reliable quantum machines, researchers need a way to accurately determine what a quantum device is actually doing.

Quantum process tomography (QPT) is a standard method for this. However, traditional QPT becomes very costly as the system grows, because the number of required measurements and calculations increases rapidly with the number of qubits.

To address this challenge, a research team from Tohoku University, the Nara Institute of Science and Technology (NAIST), and the University of Information Technology (Vietnam National University, Ho Chi Minh City) has introduced a new framework called compilation-based quantum process tomography (CQPT). The work is published in Advanced Quantum Technologies.

Debugging a quantum processor: New method pinpoints qubit errors during logical operations

Researchers at the University of Innsbruck, together with partners from Sydney and Waterloo, have presented a new diagnostic method for quantum computers. It makes errors in individual quantum bits visible during logical calculation and evaluates them. The new method was demonstrated on an ion trap quantum processor in Innsbruck. It can be used to identify critical error sources—a key to developing more robust, fault-tolerant quantum processors.

In Physical Review X, the researchers present a scalable method that can be used to reliably characterize logical quantum operations at the level of the underlying quantum bits. Cycle error reconstruction identifies which physical errors influence the performance of logically encoded gates.

“With cycle error reconstruction, we can quantitatively capture the error structure and clearly distinguish between correctable and uncorrectable contributions,” says first author Robert Freund from the Department of Experimental Physics.

Full dimensional control of structured microwaves based on microcombs

Using a chip-based microcomb, full dimensional control of structured microwaves is demonstrated, including vortex-microwave generation, submicrosecond spatiotemporal mode switching, broadband phase–frequency response tuning and wide-angle two-dimensional beam steering. These capabilities are applied in a structured-microwave-based integrated sensing and communication system.

Australian consortium to develop quantum biotechnology platform to transform Alzheimer’s treatment discovery

“Our system provides a pathway towards a fast, scalable tool for measuring real-time brain activity in synthetic tissue cultures that replicate human brain tissue,” Associate Professor Simpson said.

If successful, this brain-on-chip technology could help evaluate the effectiveness of treatments for neurological diseases, including Alzheimer’s, schizophrenia, epilepsy and anxiety, in the laboratory before moving into expensive and complex human trials.

Quantum internet materializes in Germany due to a 30-kilometer breakthrough

Something once thought too delicate for real cities just survived them. A quiet test in Germany hints that the next internet may be both unbreakable and already under our feet.

On a 30-kilometer loop of commercial fiber in Berlin, researchers just teleported data while ordinary internet traffic flowed on the same line without a hiccup. The feat, executed by T-Labs with Qunnect’s Carina platform, kept delicate quantum states steady against city vibrations and temperature swings, hitting 95 percent fidelity in real time. It shows that today’s networks can carry tomorrow’s quantum links, with stakes that range from unbreakable cryptography to connected quantum computers. For Deutsche Telekom’s Abdu Mudesir, it also signals a path to European technological sovereignty as the system scales to longer distances and more nodes.

All-in-Focus Fourier Ptychographic Microscopy via 3D Implicit Neural Representation

Microscopy has long been essential to biomedical research, enabling detailed analyses of complex samples. Fourier ptychographic microscopy (FPM), a computational imaging technique, provides high-resolution, wide-field images without requiring extensive hardware modifications. However, current FPM algorithms struggle with samples exhibiting depth variations, such as tilted or 3-dimensional (3D) objects. The limited depth of field (DoF) leads to images with only focal-plane areas in sharp focus, while regions outside appear blurred. To address this limitation, we propose an all-in-focus FPM algorithm using physics-informed 3D neural representations to reconstruct sharp, wide-field images of 3D objects under limited DoF. Unlike previous methods, our approach samples the full depth range to create a 3D feature volume that incorporates spatial and depth information.

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