Systems with indefinite causal order must be nonlocal in space–time.
Category: quantum physics – Page 42
A cryogenic microscope reveals the atomic-scale processes that disrupt the charge-ordered state in a material as the temperature rises.
Many of the exotic materials being investigated for next-generation technologies exhibit charge order, a state in which the electrons arrange themselves into a periodic pattern, such as stripes of high and low electron density. Researchers have now shown that they can track the evolution of this state as it warms up and melts away by using a cryogenic electron microscope [1]. Their experimental approach offers a new way to explore the interactions between different phases of quantum materials, which could inform the development of future electronic and data storage devices.
In certain materials with strongly interacting electrons, charge order appears—usually below room temperature—as an electron density that varies periodically in a pattern of stripes, a checkerboard, or a more complicated 3D structure. Researchers want to understand this phase because it coexists and interacts with other states and properties of the material, many of which are useful for novel devices and technologies. In high-temperature superconductors, for example, charge order is known to suppress the material’s superconducting behavior. In other materials, strong coupling between charge order and ferromagnetism can trigger colossal magnetoresistance, a property that could be exploited in magnetic storage devices.
To develop scalable and reliable quantum computers, engineers and physicists will need to devise effective strategies to mitigate errors in their quantum systems without adding complex additional components. A promising strategy to reduce errors entails the use of so-called dual-type qubits.
These are qubits that can encode quantum information in a system across two different types of quantum states. These qubits could increase the flexibility of quantum computing architectures, while also reducing undesirable crosstalk between qubits and enhancing a system’s operational fidelity.
Researchers at Tsinghua University and other research institutes in China recently realized an entangling gate between dual-type qubits in an experimental setting.
It’s expected that the technology will tackle myriad problems that were once deemed impractical or even impossible to solve. Quantum computing promises huge leaps forward for fields spanning drug discovery and materials development to financial forecasting.
But just as exciting as quantum computing’s future are the breakthroughs already being made today in quantum hardware, error correction and algorithms.
NVIDIA is celebrating and exploring this remarkable progress in quantum computing by announcing its first Quantum Day at GTC 2025 on Thursday, March 20. This new focus area brings together leading experts for a comprehensive and balanced perspective on what businesses should expect from quantum computing in the coming decades — mapping the path toward useful quantum applications.
Physicists discover a unique quantum behavior that offers a new way to manipulate electron-spin and magnetization to push forward cutting-edge spintronic technologies, like neuromorphic computing.
Symmetry plays a crucial role in understanding fundamental phenomena such as conservation laws, the classification of phases of matter, and their transitions. Recently, researchers have been exploring ways to manipulate symmetries in quantum many-body systems with time-dependent driving protocols and, in particular, engineering new symmetries that do not naturally occur. This significantly enriches the toolbox for quantum simulation and computation, and has led to many exciting discoveries of nonequilibrium phases such as discrete time crystals. However, controlling multiple symmetries—especially in a simple and experimentally friendly way—has remained a challenge. In this work, we propose a novel method to engineer hierarchical symmetries by time-dependent protocols.
By carefully controlling how symmetry-indicating observables evolve over time, we show how to create a sequence of symmetries that emerge one after another, each with distinct properties. Our method relies on a recursive construction that hierarchically minimizes the effects of symmetry-breaking processes. This leads to a corresponding sequence of prethermal steady states with controllable lifetimes, each exhibiting a lower symmetry than the preceding one. We illustrate this protocol with several examples, demonstrating how different types of order can emerge through hierarchical symmetry breaking.
This toolbox of hierarchical symmetries opens a new path to stabilizing quantum states and controlling unwanted symmetry-breaking effects, which can be particularly useful in quantum computing and quantum simulation. The construction applies to classical and quantum, fermionic and bosonic, interacting and noninteracting systems. The underlying mechanism generalizes state-of-the-art dynamical decoupling techniques and is implementable on present-day quantum simulation platforms.
US researchers send quantum entangled signal over commercial fiber optic network without requiring any downtime, a major achievement.
A huge number of ultracold atoms have been corralled into a grid that could form the basis of the next largest quantum computer.
The operation and performance of quantum computers relies on the ability to realize and control entanglement between multiple qubits. Yet entanglement between many qubits is inherently susceptible to noise and imperfections in quantum gates.
In recent years, quantum physicists and engineers worldwide have thus been trying to develop more robust protocols to realize and control entanglement. To be most effective for real-world applications, these approaches should reliably support long-range entanglement, or in other words ensure that qubits remain entangled even when they are separated by large distances.
Researchers at IBM Quantum, University of Cologne and Harvard University set out to demonstrate one of these protocols in an experimental setting.
Physicists have spent more than a century measuring and making sense of the strange ways that photons, electrons, and other subatomic particles interact at extremely small scales. Engineers have spent decades figuring out how to take advantage of these phenomena to create new technologies.
In one such phenomenon, called quantum entanglement, pairs of photons become interconnected in such a way that the state of one photon instantly changes to match the state of its paired photon, no matter how far apart they are.
Nearly 80 years ago, Albert Einstein referred to this phenomenon as “spooky action at a distance.” Today, entanglement is the subject of research programs across the world—and it’s becoming a favored way to implement the most fundamental form of quantum information, the qubit.