Matter-wave interferometry has become a ubiquitous and reliable tool for studying fundamental forces and phenomena and for realizing sensitive measurements. Our recent experiments with metal clusters have allowed us to demonstrate the quantum-wave nature of nanoparticles exceeding 170 kDa. Interestingly, the same experiments also allow for the preparation of moiré fringes of objects in the megadalton range. In this work, we demonstrate such moiré fringes of large sodium nanoparticles and, owing to the platform's stability, resolve nanometer-scale fringe displacements between successive contrast revivals, directly observing the predicted π-phase flip as a half-period shift. We further discuss how this feature turns the interferometer into a device for advanced sensing, even when operating in the regime where the predictions of quantum and classical physics merge.
Matter-wave interferometers, either with electrons, atoms or molecules, owe their sensitivity to the accuracy of phase-shift measurements. One may, however, raise the question whether the shift undergone by interference fringes, when external forces are applied, actually differs from the shift of classical trajectories. For the case of a magnetic perturbation, we provide experimental evidence and a vector demonstration that interference patterns only undergo a global shift. The experiment is performed with the photodetachment microscope, with a uniform magnetic field superimposed over the whole volume accessible to the interfering electron. Identity of the fringe and trajectory shifts is established for any two-wave interferometer using charged particles, submitted to a magnetic field.
Abstract Otto Stern became famous for molecular beam physics, matter-wave research and the discovery of the electron spin, with his work guiding several generations of physicists and chemists. Here we discuss how his legacy has inspired the realization of universal interferometers, which prepare matter waves from atomic, molecular, cluster or eventually nanoparticle beams. Such universal interferometers have proven to be sensitive tools for quantum-assisted force measurements, building on Stern’s pioneering work on electric and magnetic deflectometry. The controlled shift and dephasing of interference fringes by external electric, magnetic or optical fields have been used to determine internal properties of a vast class of particles in a unified experimental framework.