Physicists exploit a quantum rule to create a new kind of crystal

A. Helemans

The smaller they make their devices, the closer electronics engineers come to entering the world of quantum mechanics, that wonderland where the rules of physics differ drastically from those of the macroscopic world people experience with their senses. In one example, physicists and engineers are creating so-called quantum dots and are investigating how to use them in new forms of electronics. They aspire to transmit data not by tiny currents, but by single electrons that hop from one quantum dot to the next. Probably the one thing generally known about quantum mechanics is that matter-despite its particulate nature-may behave like a wave. This idea was emphasized once again last year when a team at the Massachusetts Institute of Technology (MIT), in Cambridge, produced coherent beams of matter in what the group refers to as an atom laser. (The same group just two years ago produced an entirely new state of matter known as Bose-Einstein condensates.) Elsewhere, scientists in France have succeeded in detecting decoherence, the transition from the quantum world into the macroscopic world, by contriving systems that can be in two quantum states at the same time, albeit briefly. Also in France, physicists have shown how to exploit chaos to encrypt optically transmitted data. This finding might eventually be useful in ultrafast applications, such as the scrambling and unscrambling of television signals transmitted over optical fibers.

Elizabeth Pennisi

Tobias Donner

Alfred Landé

SIXTY-SEVEN YEARS AGO Max Planck initiated the quantum age, but its conceptual content still mystifies the student. And the efforts to explain the basic mathematical rules of the theory by developing them from certain fundamental principles (wave-particle duality and complementarity) beg the question since those rules and principles themselves are of a quantum character. For this reason several theorists have gone one step further in their analysis and have established a system of axioms that do not include any quantum rule explicitly. However the axioms—I refer to the 14 theses of Fritz Bopp in the Heisenberg festschrift and those of Günther Ludwig in his Grundlagen der Quantenmechanik—are of a highly abstract mathematical kind and will hardly satisfy the physicist's desire for an explanation of the bewildering quantum theory.

Chloe Watson

Reyes Juárez‐Ramírez, Christian Xavier Navarro Cota, Samantha Jiménez +5 more

The principles of quantum mechanics – superposition, entanglement, measurement, and decoherence – form the foundation of quantum computing. Qubits, which are abstract objects having a mathematical expression to implement the rules of quantum physics, are the fundamental building blocks of computation. Software is a key component of quantum computing, along with quantum hardware. Algorithms make up software, and they are implemented using logic gates and quantum circuits. These qualities make quantum computing a paradigm that non-physicists find difficult to comprehend. It is crucial to incorporate a conceptual framework of the principles upon which quantum computing is founded into this new method of creating software. In this paper, we present a kind of taxonomical view of the fundamental concepts of quantum computing and the derived concepts that integrate the emerging discipline of quantum software engineering. Because the systematic review's main goal is to identify the core ideas behind quantum computing and quantum software, we conducted a quasi-systematic mapping as part of the review process. The findings can serve as a starting point for computer science teachers and students to address the study of this field.