Issues
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Cover Image
Cover Image
Cover: Although it’s natural to think of our world classically, quantum mechanics is all around us, and early debates about quantum theory, epitomized by Schrödinger’s cat, have morphed into real-world quantum applications. In this special issue, we present articles from the Physics Today archives that describe the birth of modern quantum mechanics, the emergence of several key concepts, and emerging applications that have the potential to transform both science and society. (Cover design by Three Ring Studio.)
From the Editor
Our quantum world
Issues and Events
2025 is the International Year of Quantum Science and Technology
Building awareness and inspiring a future workforce are two aims of the UN-designated quantum year.
Special Issue: Our Quantum World
Stories from the early days of quantum mechanics
A colloquium delivered to the University of Toronto physics department on 5 April 1979 by the master of molecular beams offers a fresh look at an earlier era.
Quantum electrodynamics
Magic moments with John Bell
John Bell, with whom I had a fruitful collaboration and warm friendship, is best known for his seminal work on the foundations of quantum physics, but he also made outstanding contributions to particle physics and accelerator physics.
Is the Moon there when nobody looks? Reality and the quantum theory
Einstein maintained that quantum metaphysics entails spooky actions at a distance; experiments have now shown that what bothered Einstein is not a debatable point but the observed behavior of the real world.
Quantum entanglement: A modern perspective
It’s not your grandfather’s quantum mechanics. Today, researchers treat entanglement as a physical resource: Quantum information can now be measured, mixed, distilled, concentrated, and diluted.
From quantum cheating to quantum security
For thousands of years, code-makers and code-breakers have been competing for supremacy. Their arsenals may soon include a powerful new weapon: quantum mechanics.
Photon science and quantum control
Recent advances in laser technology have hastened developments in other fields—precision measurement, atomic cooling, gravitational-wave sensing, quantum computing, cryptography, and many more. Like the laser itself, those fields may transform society.
What’s under the hood of a quantum computer?
Many layers lie between everyday users and the delicate, error-prone hardware they manipulate.
Squeezing quantum noise
You can’t beat the Heisenberg uncertainty principle, but you can engineer systems so that most of the uncertainty is in the variable of your choice. Doing so can improve the precision of delicate measurements.
