The wavelike nature of fullerenes, recently detected by the the Zelinger group in Vienna, shows the de Broglie wave–particle duality can be shown for bodies with a molecular mass as large as 1000 Da. The experiment itself is described and its consequences on the question “what is a particle?” are discussed.
The standard quantum theory has not taken into account the size of quantum particles, the latter being implicitly treated as material points. The recent interference experiments of Zeilinger [3] with large molecules like fullerenes and the thought experiments of Bozic et al [7] with asymmetrical Young slits make it possible today to take into account the particle size. We present here a complete study of this phenomenon where our simulations show differences between the particles density after the slits and the modulus square of the wave function. Then we propose a crucial experiment that allows us to reconsider the wave-particle duality and to test the existence of the Broglie-Bohm trajectories for indistinguishable particles.
Summary form only given, as follows. In a recent experiment we were able to demonstrate the de Broglie wave character of the fullerene molecule C/sub 60/ by diffraction at a free standing material grating. This proves that it is possible to preserve quantum coherence almost completely in the external degrees of freedom of a hot, massive and complex object over a long time and distance. This may seem astonishing in the light of the fact that the fullerenes were produced in a thermal source which was kept at about 900 K. At such a high temperature the de Broglie wavelength is about 400 times smaller than the size of the molecule (/spl lambda//sub dB//spl sim/25 pm), all internal degrees of freedom (174 different vibrational modes, and rotational modes up to J>100) are excited and the molecules may emit a few infrared photons (blackbody radiation and vibrational quanta) during their time of flight through the apparatus. Our published measurements so far have been essentially consistent with the absence of decoherence during the time of flight of the molecules. The interference contrast in all experiments has however so far been limited by the thermal velocity spread and the finite collimation of the fullerene beam.
Wave–particle duality is frequently the first topic students encounter in elementary quantum physics. Although this phenomenon has been demonstrated with photons, electrons, neutrons, and atoms, the dual quantum character of the famous double-slit experiment can be best explained with the largest and most classical objects, which are currently the fullerene molecules. The soccer-ball-shaped carbon cages C60 are large, massive, and appealing objects for which it is clear that they must behave like particles under ordinary circumstances. We present the results of a multislit diffraction experiment with such objects to demonstrate their wave nature. The experiment serves as the basis for a discussion of several quantum concepts such as coherence, randomness, complementarity, and wave–particle duality. In particular, the effect of longitudinal (spectral) coherence can be demonstrated by a direct comparison of interferograms obtained with a thermal beam and a velocity selected beam in close analogy to the usual two-slit experiments using light.
In matter wave interferometry, detectors detect individual particles; the wave picture (interference pattern) emerges only as a statistical aggregation, after a large number of particles have been detected. Feynman, mystified by such facts, declared that 'nobody understands quantum mechanics'. A few decades later, Ketterle summed up the situation as 'one gets used to preparing waves and detecting particles'. But why are matter waves detected only as particles? Is there a law of nature forbidding their detection as waves? This question does not seem to have been addressed. The present communication suggests that it may be possible to detect matter waves as waves if there exists a nonlocal interaction - due to wave-particle duality - that causes a nonlocal transfer of energy and momentum from microscopic objects to mesoscopic or macroscopic ones. It describes the principle of a possible wave detector and the scheme of an experiment. The experiment may be feasible in the foreseeable future with a mesoscopic detector made of carbon nanostructures, or in an earth satellite in an elliptical orbit. The detection of a single atom or molecule as a wave will have enormous consequences, both practical and conceptual.
The de Broglie wavelength λ= h/mv of simple particles (photon, electron, neutron) atoms (helium, neon) and molecules (fullerene, fluorous porphyrin) deduced from the de Broglie (dB) relation and those measured by double slits interferometry are compared.The de Broglie relation is verified in very large domains of velocity v and mass m of the particles, respectively 8 and 13 orders of magnitude.In this paper one analyses the interference spectra of photons and electrons and give the Intensity Relations IR(II-DI) between the interference intensity (II) by two slits and the diffracted intensity (DI) by one slit.The double slits interference in the de Broglie-Bohm interpretation is an interference of particle and pilot waves, internal and external waves each passing by a different slit.The velocities of these waves are discussed.From the universal de Broglie relation and the relation vp = vw between the particle and pilot waves one shows that only in the domain of the maximum of the light spectrum (λm~ 550 µm) the dB relation leads to the Plank-Einstein (PE) relation hν=mc 2 .A measure of the mass of the photon m* = 4 10 -36 Kg is deduced.The de Broglie relation for different wave lengths shows that the PE relation must be modified, the velocity of light is not constant as shown by various experiments: Global Positioning Systems GPS, red shift in astronomy etc.This has been discussed by Marmet in years 2000.The same conclusion was given by Sato in 2010 for electromagnetic waves.The trajectories of electrons observed by Jönsson by double slits interferometry and then calculated by Gondran according to the de Broglie-Bohm interpretation are then analyzed in detail.The correlations observed between the properties of these trajectories at short and long distances from the slits permit to give the general equation of the trajectories.The origin of these properties is discussed in the framework model of De Broglie and Bohm, assuming that at any point the intensity of the two waves (particle and pilot wave) passing by the 2 slits are deceasing functions of the distance to the slits.The changes of direction of the trajectories are explained.