  In the early days of quantum mechanics, Schr\"odinger noticed that
oscillations of a wave packet in a one-dimensional harmonic potential well are
periodic and, in contrast to those in anharmonic potential wells, do not
experience distortion over time. This original idea did not find applications
up to now since an exact one-dimensional harmonic resonator does not exist in
nature and has not been created artificially. However, an optical pulse
propagating in a bottle microresonator (a dielectric cylinder with a
nanoscale-high bump of the effective radius) can exactly imitate a quantum wave
packet in the harmonic potential. Here, we propose a tuneable microresonator
that can trap an optical pulse completely, hold it as long as the material
losses permit, and release it without distortion. This result suggests the
solution of the long standing problem of creating a microscopic optical buffer,
the key element of the future optical signal processing devices.
