Tine Crystal

A time crystal or space-time crystal is an open system in non-equilibrium with its environment that exhibits time translation symmetry breaking (TTSB). In March 2017, it was reported that the theoretical concept of time crystals had been proven, showing that, contrary to what is indicated by the laws of thermodynamics, it is impossible for these crystals to be in equilibrium with their environment over time.^[1]

The idea of a time crystal was first put forward by Nobel laureate and MIT professor Frank Wilczek in 2012.^[a] Space-time crystals extend the ordinary three-dimensional symmetry seen in crystals to include the fourth dimension of time; a time crystal spontaneously breaks the symmetry of time translation. The crystal's pattern repeats not in space, but in time, which allows for the crystal to be in perpetual motion.^[3] Time crystals are closely related to the concepts of zero-point energy and the dynamical Casimir effect.^[b]

In 2016, Norman Yao and his colleagues from the University of California, Berkeley, put forward a concrete proposal that would allow time crystals to be created in a laboratory environment.^[c] Yao's blueprint was then used by two teams, a group led by Christopher Monroe at the University of Maryland^[d] and a group led by Mikhail Lukin at Harvard University,^[e] who were both able to successfully create a time crystal. Both experiments were published in the journal Nature in March 2017.^[7]

Time crystals are thought to exhibit topological order,^[8] an emergent phenomenon, in which nonlocal correlations encoded in the whole wave-function of a system allow for fault tolerance against perturbations, thus allowing quantum states to stabilize against decoherence effects that usually limit their useful lifetime. Preventing decoherence has a wide range of implications: The efficiency of some information theory and quantum thermodynamic tasks can be greatly enhanced when using quantum correlated states. It is also thought that time crystals could provide deeper understanding of the theory of time.^[9]