Researchers have quantified the performance of a quantum processor built from semiconductor quantum dots, charting the challenges to scaling up the technology.
Category: quantum physics
New state of matter discovered in a quantum material
At TU Wien, researchers have discovered a state in a quantum material that had previously been considered impossible. The definition of topological states should be generalized.
The work is published in Nature Physics.
Quantum physics tells us that particles behave like waves and, therefore, their position in space is unknown. Yet in many situations, it still works remarkably well to think of particles in a classical way—as tiny objects that move from place to place with a certain velocity.
Neutral-atom arrays, a rapidly emerging quantum computing platform, get a boost from researchers
For quantum computers to outperform their classical counterparts, they need more quantum bits, or qubits. State-of-the-art quantum computers have around 1,000 qubits. Columbia physicists Sebastian Will and Nanfang Yu have their sights set much higher.
“We are laying critical groundwork to enable quantum computers with more than 100,000 qubits,” Will said.
In a paper published in Nature, Will, Yu, and their colleagues combine two powerful technologies— optical tweezers and metasurfaces—to dramatically scale the size of neutral-atom arrays.
Quantum simulator reveals how vibrations steer energy flow in molecules
Researchers led by Rice University’s Guido Pagano used a specialized quantum device to simulate a vibrating molecule and track how energy moves within it. The work, published Dec. 5 in Nature Communications, could improve understanding of basic mechanisms behind phenomena such as photosynthesis and solar energy conversion.
The researchers modeled a simple two-site molecule with one part supplying energy and the other receiving it, both shaped by vibrations and their environment. By tuning the system, they could directly observe energy moving from donor to acceptor and study how vibrations and energy loss influence that transfer, providing a controlled way to test theories of energy flow in complex materials.
“We can now observe how energy moves in a synthetic molecule while independently adjusting each variable to see what truly matters,” said Pagano, assistant professor of physics and astronomy.
The Quantum Security Problem No One Is Ready For
Quantum computers are expected to deliver dramatic gains in processing speed and capability, with the potential to reshape fields ranging from scientific research to commercial innovation.
However, those same advantages could also make these machines attractive targets for cyberattacks, according to Swaroop Ghosh, a professor of computer science and electrical engineering at the Penn State School of Electrical Engineering and Computer Science.
Ghosh and co-author Suryansh Upadhyay, who recently earned his doctorate in electrical engineering from Penn State, examined these concerns in a new research paper that outlines key security weaknesses in current quantum computing systems. Published in the Proceedings of the Institute of Electrical and Electronics Engineers (IEEE), the study argues that protecting quantum computers will require more than software safeguards, emphasizing the importance of securing the underlying hardware as well.
Quantum-dot device can generate multiple frequency-entangled photons
Researchers have designed a new device that can efficiently create multiple frequency-entangled photons, a feat that cannot be achieved with today’s optical devices. The new approach could open a path to more powerful quantum communication and computing technologies.
“Entangling particles efficiently is a critical capability for unlocking the full power of quantum technologies—whether to accelerate computations, surpass fundamental limits in precision measurement, or guarantee unbreakable security using the laws of quantum physics,” said Nicolas Fabre from Telecom Paris at the Institut Polytechnique de Paris.
“Photons are ideal because they can travel long distances through optical fibers or free space; however, there hasn’t been a way to efficiently generate frequency entanglement between more than two photons.”
Negative Energy ‘Ghosts’ Flashing in Space Could Reveal New Physics
A ‘boom’ of light that appears when a particle exceeds the speed of light set by a medium could, in other contexts, signal a kind of quantum instability that could trigger what’s known as vacuum decay.
If ever spotted in the emptiness of space, according to theoretical physicist Eugeny Babichev of the University of Paris-Saclay, the eerie blue glow of Cherenkov radiation could be interpreted as a manifestation of negative-energy ghost perturbations.
Why does it matter? Because our current theory of gravity is incomplete, and such a signal would offer rare insight into how spacetime behaves in regimes where existing theories break down, and potentially narrow the search for better models.
Scientists realize a three-qubit quantum register in a silicon photonic chip
Quantum technologies are highly promising devices that process, transfer or store information leveraging quantum mechanical effects. Instead of relying on bits, like classical computers, quantum devices rely on entangled qubits, units of information that can also exist in multiple states (0 and 1) at once.
A research team at the University of California Berkeley (UC Berkeley) supervised by Alp Sipahigil recently demonstrated the potential of leveraging atomic-scale defects on silicon chips, known as T-centers, to create small multi-qubit memory units that store quantum information (i.e., quantum registers).
Their paper, published in Nature Nanotechnology, could open new possibilities for the development of quantum technologies that are based on silicon, which is the most widely used material within the electronics industry.
DNA Gene’s Basic Structure as a Nonperturbative Circuit Quantum Electrodynamics: Is RNA Polymerase II the Quantum Bus of Transcription?
Previously, we described that Adenine, Thymine, Cytosine, and Guanine nucleobases were superconductors in a quantum superposition of phases on each side of the central hydrogen bond acting as a Josephson Junction. Genomic DNA has two strands wrapped helically around one another, but during transcription, they are separated by the RNA polymerase II to form a molecular condensate called the transcription bubble. Successive steps involve the bubble translocation along the gene body. This work aims to modulate DNA as a combination of n-nonperturbative circuits quantum electrodynamics with nine Radio-Frequency Superconducting Quantum Interference Devices (SQUIDs) inside. A bus can be coupled capacitively to a single-mode microwave resonator. The cavity mode and the bus can mediate long-range, fast interaction between neighboring and distant DNA SQUID qubits.