Detecting the Casimir Energy

Trustees Of Boston University, Boston

Investigators

Abstract

Title: Detecting the Casimir Energy: A Quantum Mechanical Effect with Significant Real-World Implications Abstract: Non-technical: In the classical world, a vacuum consists of nothing. No fields, forces or particles exist. However, the world we live in is not classical but controlled at the atomic scale by the rules of quantum mechanics (QM). Quantum mechanics has a number of rules and effects that defy our normal, real-world intuition. An example is the quantum mechanical vacuum. In such a vacuum, electrical and magnetic fields can and do exist albeit for short periods of time and over small length scales. One can think of the vacuum as the surface of a pond. The classical vacuum is a still pond with no waves or ripples. A boat floating on this pond never moves. However, the QM pond has waves that propagate for a short distance and then die out. These waves can move a boat on the surface. The Casimir effect is seen when one creates a set of conditions where these waves exert measurable forces on small, nanoscale objects (our boat). In classical physics, these forces should not exist but quantum mechanically they do exist and can be detected. These QM effects manifest themselves at the nanoscale and building devices and systems at this size requires that we understand them and learn how to work with them. Specifically, theoretical predictions suggest that these QM waves will change the transition temperature of a superconductor and we aim to observe this effect. Beyond interesting physics, such an effect may have implications for the existence of wormholes in space. While it is not fair to say we are looking for these, we will be doing experiments in a regime where theories by some of the world?s most eminent scientists say they may occur. We do plan to keep our eyes open. Technical: We propose research that will create MEMS devices for detecting the Casimir Energy. The Casimir effect is a result of the appearance of quantum fluctuations in the electromagnetic vacuum. A previous set of experiments done by a number of researchers have used MEMS parallel plate capacitors to detect the Casimir effect by measuring the small attractive force these fluctuations exert on the device. In this new set of experiments, we propose to directly detect the Casimir Energy in the vacuum modified by the presence of metallic parallel plates, a fundamentally new measurement of considerable interest to the theoretical physics community. Our approach uses a superconducting film as a sensor. The changes in the Casimir Energy within the superconductor volume is expected to shift the superconducting transition temperature because of an interaction between it and the superconducting condensation energy. The experiment we propose consists of taking a superconducting film, carefully measuring its transition temperature, bringing a conducting plate close to the film, creating a Casimir cavity, and then measuring the transition temperature again. The expected shifts will be small, ~1mK, comparable to the normal shifts one sees in cycling superconducting films to cryogenic temperatures and so using MEMS plates and doing this in situ is the only practical way to obtain accurate, reproducible data. We propose to use a MEMS device where the location of the plate can be changed while at low temperatures and look for this effect. Mechanically oscillating the MEMS plate position will modulate the effect and eliminate 1/f noise and long-term drifts from the measurement.