All articles tagged with #quantum mechanics
Physicists built a working version of quantum mechanics using only real numbers, recreating all predictions of the standard theory by replacing the usual complex-number tensor product with a real-number rule and a bookkeeping flag system. The approach shows complex numbers aren’t fundamental to quantum mechanics, though the work currently covers finite systems and does not alter experimental predictions.
A Science perspective shows how quantum mechanics evolved from a puzzling 20th‑century idea to the foundation of lasers, microchips, secure communications, and emerging quantum computers, driven by coherence and entanglement; the piece highlights quantum heat engines that may exceed classical limits and notes expanding applications in biology, gravity, and turbulence, with open questions about quantizing gravity and the future impact of quantum technologies.
New theoretical ideas suggest time may emerge from gravity via Shape Dynamics, while open quantum systems could host two arrows of time; other approaches explore time as potentially emergent or even illusory, with concepts like tachyons and quantum entanglement hinting at multi-dimensional or timeless frameworks.
Physicists simulated slicing a single photon with a shutter and found that the global quantum state becomes a complex mixture spanning zero to infinitely many photons. Locally, measurements on one side can reveal a single-photon state while the other side appears as vacuum, illustrating a paradoxical, nonlocal distribution and raising questions about the nature of particles and causality. The work, reported in Physical Review Letters, could lead to a clearer way to describe particle interactions and extend to other quantum particles like electrons; in realistic setups the infinite case requires an idealized infinitely fast shutter.
Physicists propose extending special relativity to include observers moving faster than light, suggesting that keeping the superluminal branch yields a many-path, probabilistic view of particles that aligns relativity with quantum behavior. In a 1+3 spacetime this implies three time dimensions and one spatial dimension, offering a conceptual path to connect causality, quantum indeterminacy, and the Higgs mechanism—though the work is purely theoretical and lacks experimental proof.
The piece revisits Schrödinger’s 1935 cat-in-a-box thought experiment, used to critique interpretations of quantum mechanics by suggesting a system could be in a live-and-dead superposition until observed. It notes Schrödinger’s letter to Einstein and the ongoing debate over whether reality collapses to a definite state at measurement, highlighting the origin and stakes of the quantum measurement problem.
APS’s large survey of about 1,660 participants—ranging from researchers to science enthusiasts—reveals widespread disagreement on core physics questions, from the Big Bang to quantum gravity. The Big Bang is widely seen as a hot, dense state (68%), not necessarily the absolute beginning (25%). Quantum interpretations are not universally accepted: Copenhagen leads at around 36%, with many opting for other theories or 'no opinion.' About half agree on cosmic inflation, while dark energy and ΛCDM show no clear majority, with evolving dark energy edging ahead slightly. Only a minority subscribe to specific quantum gravity views, with string theory leading among them. The results underscore that physics frontiers remain active and data and theory must advance to resolve these debates.
A team studying quantum-collapse models (Diósi–Penrose and Continuous Spontaneous Localization) linked to gravity finds that time itself may have a minute intrinsic uncertainty, implying a fundamental limit on how precisely time can be measured. The effect is unimaginably small and would not affect current timekeeping, but it suggests deep connections between quantum mechanics and gravity and offers a way to experimentally distinguish collapse models from standard quantum theory.
Vienna and Duisburg-Essen researchers show that sodium nanoparticle clusters (~8 nm, >170,000 amu) can exhibit quantum interference, existing in a superposition as they pass through three UV-laser diffraction gratings. Achieving a macroscopicity value of μ = 15.5, the experiment extends quantum behavior toward larger scales and opens the door to studying bigger particles and precision sensing.
Quantum mechanics has evolved from a puzzling theory to the backbone of modern technology, powering lasers, chips, quantum computing, and secure communications. Texas A&M physicist Marlan Scully surveys the journey—from Schrödinger’s cat to coherence and entanglement enabling new sensors and cryptography, to quantum heat engines that can exceed classical limits. The reach extends into biology and cosmology, while open questions about unifying gravity with quantum theory promise a continued scientific adventure.
The piece argues that the 'reality' of a multiverse hinges on definition: while quantum mechanics’ many-worlds view and string theory’s landscape offer frameworks in which multiple universes could exist, there is no direct evidence for other universes. Indirect hints might come from how these theories predict physics at tiny scales or high-energy experiments, but proving a multiverse remains elusive.
A Vienna team extends Bell-test ideas to indefinite causal order, using entangled photons arranged so that the sequence A→B or B→A depends on polarization. The observed correlations differ from local-hidden-variable predictions by 18 standard deviations, suggesting quantum processes can exist in a superposition of temporal orders. However, notable loopholes remain (photon loss, limited separation) and further experiments are needed to close them, though the work points toward broader applications of time-uncertain quantum processes.
Physicists reveal a measurement-based feedback protocol that can steer a monitored quantum system’s evolution to mimic reversed time, effectively reshaping the arrow of time and enabling potential energy extraction in quantum devices; while not time travel, the approach could boost quantum batteries and algorithms, with plans to test on superconducting qubits.
An interview about Paul Davies’s book Quantum 2.0 explains how the original quantum mechanics (Quantum 1.0) gave us technologies like lasers, chips, and MRI, and how Quantum 2.0 involves manipulating individual quanta to encode information in the particles themselves, signaling a new tech revolution. The discussion spans quantum biology, the rise of quantum AI, and the tantalizing prospect of mind–machine interfaces, while noting ongoing debates about how quantum reality relates to everyday experience and imagining a potential Quantum 3.0 ahead.
A Wellesley College study found rats given a microtubule-stabilizing treatment stayed conscious longer under anesthesia, lending experimental support to Orch OR—the idea that consciousness arises from quantum processes in the brain—and suggesting quantum effects might persist at physiological temperatures; although controversial, the result fuels the debate on whether consciousness could extend beyond the brain, if validated.