John Bush explores the completeness of quantum theory, hydrodynamic quantum analogs, and the field of pilot-wave hydrodynamics.
Category: quantum physics
Detecting strong-to-weak symmetry breaking might be impossible, study shows
When a system undergoes a transformation, yet an underlying physical property remains unchanged, this property is referred to as “symmetry.” Spontaneous symmetry breaking (SSB) occurs when a system breaks out of this symmetry when it is most stable or in its lowest-possible energy state.
Recently, physicists realized that a new type of SSB can occur in open quantum systems, systems driven by quantum mechanical effects that can exchange information, energy or particles with their surrounding environment. Specifically, they realized that the symmetry in these systems can be “strong” or “weak.”
A strong symmetry entails that both the open system and its surrounding environment individually obey the symmetry. In contrast, a weak symmetry takes place when the system and the environment only follow a symmetry when they are taken together.
On-demand electronic switching of topology achieved in a single crystal
University of British Columbia (UBC) scientists have demonstrated a reversible way to switch the topological state of a quantum material using mechanisms compatible with modern electronic devices. Published in Nature Materials, the study offers a new route toward more energy efficient electronics based on topologically protected currents rather than conventional charge flow.
“Conventional electronics involve currents of electrons that waste energy and generate heat due to electrical resistance. Topological currents are protected by symmetry, and so they are promising for new types of electronics with significantly less dissipation,” said Dr. Meigan Aronson, an investigator with UBC’s Stewart Blusson Quantum Matter Institute and the Department of Physics and Astronomy.
“Our research uncovers a specific mechanism where the addition or subtraction of electrical charge can drive a reversible topological transition in the crystal, switching it from a metal that can conduct charge to an insulator that can’t. This is a key step towards the implementation of a new type of low-dissipation electronics based on symmetry and topology, and not simply on charge.”
Controlling quantum states in germanene using only an electric field
Researchers at the University of Twente and Utrecht University demonstrated for the first time that quantum states in the ultra-narrow material germanene can be switched on and off using only an electric field. The researchers were able to vary the electric field strength very precisely, causing the special ‘topological’ states in nanoribbons to disappear or appear.
The research, titled “Electric-Field Control of Zero-Dimensional Topological States in Ultranarrow Germanene Nanoribbons,” is published in Physical Review Letters.
Quantum computers will not use zeros and ones, but instead use quantum bits that can assume both states simultaneously. In theory, this makes them superfast and powerful, but in practice, building quantum bits is an enormous challenge: they are very sensitive to noise and quickly lose their information.
Calibrating qubit charge to make quantum computers even more reliable
Quantum computers will be able to assume highly complex tasks in the future. With superconducting quantum processors, however, it has thus far been difficult to read out experimental results because measurements can cause interfering quantum state transitions.
Researchers at Karlsruhe Institute of Technology (KIT) and Université de Sherbrooke in Québec have performed experiments that improve our understanding of these processes and have shown that calibrating the charge at the qubits contributes to fault avoidance.
Their findings have been published in Physical Review Letters.
Noise-proof quantum sensor uses three calcium ions held in place by electric fields
Researchers at the University of Innsbruck have shown that quantum sensors can remain highly accurate even in extremely noisy conditions. It’s the first experimental realization of a powerful quantum sensing protocol, outperforming all comparable classical strategies—even under overwhelming noise.
The study has been published in Physical Review Letters.
Quantum sensors promise unprecedented measurement precision, but their advantage can quickly erode in realistic environments where noise dominates.
New digital state of matter could help build stable quantum computers
Scientists have taken another major step toward creating stable quantum computers. Using a specialized quantum computer chip (an essential component of a quantum computer) as a kind of tiny laboratory, a team led by Pan Jianwei at the University of Science and Technology of China has created and studied a rare and complex type of matter called higher-order nonequilibrium topological phases.
This digital matter (not conventional physical material) is unique because its key behaviors are super-stable and located only at its corners. But this stability is only maintained when the material is constantly bombarded with energy pulses.
The work is a big deal because it shows that quantum computers can be used as reliable simulators to discover and test new stable forms of matter. This will be necessary if scientists are to create quantum computers that never break down (or are at least highly reliable), because super-stable corner behaviors are the kind of error-proof properties needed to build trustworthy quantum hardware.
Physicists create ‘quantum wire’ where mass and energy flow without friction or loss
In physical systems, transport takes many forms, such as electric current through a wire, heat through metal, or even water through a pipe. Each of these flows can be described by how easily the underlying quantity—charge, energy, or mass—moves through a material.
Normally, collisions and friction lead to resistance causing these flows to slow down or fade away. But in a new experiment at TU Wien, scientists have observed a system where that doesn’t happen at all.
By confining thousands of rubidium atoms to move along a single line using magnetic and optical fields, they created an ultracold quantum gas in which energy and mass move with perfect efficiency. The results, now published in the journal Science, show that even after countless collisions, the flow remains stable and undiminished, thus revealing a kind of transport that defies the rules of ordinary matter.
Quantum Algorithm Solves Metabolic Modeling Test
A Japanese research team from Keio University demonstrated that a quantum algorithm can solve a core metabolic-modeling problem, marking one of the earliest applications of quantum computing to a biological system. The study shows quantum methods can map how cells use energy and resources.
Flux balance analysis is a method widely used in systems biology to estimate how a cell moves material through metabolic pathways. It treats the cell as a network of reactions constrained by mass balance laws, finding reaction rates that maximize biological objectives like growth or ATP production.
No. The demonstration ran on a simulator rather than physical hardware, though the model followed the structure of quantum machines expected in the first wave of fault-tolerant systems. The simulation used only six qubits.