10 research outputs found
High-temperature quantum oscillations caused by recurring Bloch states in graphene superlattices
Cyclotron motion of charge carriers in metals and semiconductors leads to Landau quantization and magneto-oscillatory behavior in their properties. Cryogenic temperatures are usually required to observe these oscillations. We show that graphene superlattices support a different type of quantum oscillations that do not rely on Landau quantization. The oscillations are extremely robust and persist well above room temperature in magnetic fields of only a few T. We attribute this phenomenon to repetitive changes in the electronic structure of superlattices such that charge carriers experience effectively no magnetic field at simple fractions of the flux quantum per superlattice unit cell. Our work points at unexplored physics in Hofstadter butterfly systems at high temperatures
A method to measure the resonance transitions between the gravitationally bound quantum states of neutrons in the GRANIT spectrometer
We present a method to measure the resonance transitions between the
gravitationally bound quantum states of neutrons in the GRANIT spectrometer.
The purpose of GRANIT is to improve the accuracy of measurement of the quantum
states parameters by several orders of magnitude, taking advantage of long
storage of Ultracold neutrons at specula trajectories. The transitions could be
excited using a periodic spatial variation of a magnetic field gradient. If the
frequency of such a perturbation (in the frame of a moving neutron) coincides
with a resonance frequency defined by the energy difference of two quantum
states, the transition probability will sharply increase. The GRANIT experiment
is motivated by searches for short-range interactions (in particular
spin-dependent interactions), by studying the interaction of a quantum system
with a gravitational field, by searches for extensions of the Standard model,
by the unique possibility to check the equivalence principle for an object in a
quantum state and by studying various quantum optics phenomena