Quantum effects on a macroscopic scale

Tahereh Abad, Vahid Karimipour

It is well known that in a quantum phase transition (QPT), entanglement remains short ranged [Osterloh et al., Nature (London) 416, 608 (2005)]. We ask if there is a quantum property entailing the whole system which diverges near this point. Using the recently proposed measures of quantum macroscopicity, we show that near a quantum critical point, it is the effective size of macroscopic superposition between the two symmetry breaking states which grows to the scale of system size, and its derivative with respect to the coupling shows both singular behavior and scaling properties.

Tristan Farrow, Vlatko Vedral

Florian Fröwis, Pavel Sekatski, Wolfgang Dür +2 more

Large-scale quantum effects have always played an important role in the foundations of quantum theory.With recent experimental progress and the aspiration for quantum enhanced applications, the interest in macroscopic quantum effects has been reinforced.In this review, measures aiming to quantify various aspects of macroscopic quantumness are critically analyzed and discussed.Recent results on the difficulties and prospects to create, maintain, and detect macroscopic quantum states are surveyed.The role of macroscopic quantum states in foundational questions as well as practical applications is outlined.Finally, past and ongoing experimental advances aiming to generate and observe macroscopic quantum states are presented.

Philip R. Wallace

Terrence D. Clark, Helen Prance, Robert J. Prance +1 more

Raymond W. Jensen

An experiment is proposed, whose purpose is to determine whether quantum indeterminism can be observed on a truly macroscopic scale. The experiment involves using a double-slit plate or interferometer and a macroscopic mechanical switch. The objective is to determine whether or not the switch can take on an indeterminate state.