(Credit: J. Consoli/UMD)
Quantum mechanics, which describes the behavior of matter and energy on the smallest physical scales, is the most accurate theory of nature ever devised. Many of its predictions can be confirmed to 10 decimal places or more. Its principles explain a host of phenomena from the grand sweep of the Periodic Table of Elements to the everyday workings of lasers, microchips, light-emitting diodes and MRI medical scans.
The ability to understand and manipulate objects at the quantum level is among the most urgent goals of 21st century science. It is essential to progress in physics, chemistry, electronic engineering and nanotechnology, to creating new computers of unprecedented power, and to determining how atoms behave in large arrays, such as the crystals of semiconductors or the metal-oxide layers of superconductors. But researchers at JQI and elsewhere have only begun to control and exploit quantum processes, which are inherently difficult to manage for several reasons.
One is that, at quantum dimensions, objects (for example, an electron orbiting an atom's nucleus) do not have specific, fixed properties such as location or momentum. Instead, they exist in a peculiar condition called "superposition," in which each object simultaneously embodies all the properties that are possible for that object - until the act of measurement forces it to take on specific values. It is impossible to predict those values prior to measurement, although the probability of any particular value occurring can be calculated.
However, that same indeterminacy gives quantum systems an enormous potential for information processing because they can perform operations on all the superposed values at once instead of one value at a time. And even though a quantum state is unknowable prior to measurement, the states of two separate objects, such as individual atoms, can be "entangled" in ways such that the state of each is inextricably correlated with the state of the other. That phenomenon, which is the subject of intensive research at JQI, makes it possible to move quantum information from one place to another.
The intrinsically probabilistic nature of quantum behavior, the sub-microscopic dimensions and extremely short time periods over which quantum events take place, and the exotic experimental conditions required to study them, all pose substantial problems for researchers. As a result, much important work is still at a stage equivalent to the demonstration of the first transistor in 1947: the principles are generally understood, but the capacity to control specific phenomena, ensure desired outcomes and link quantum systems together reliably is largely lacking.
Yet the need is great. Major advances in a dozen areas - as well as probable economic benefits in the form of advanced synthetic materials, ultra-precise sensors, nanotechnology, new forms of data encryption and the next generation of information processors and computers - await developments in quantum science. The Joint Quantum Institute was created to hasten the pace of progress.