Lecturer: Prof. Jonathan Home
Affiliation: ETH Zürich
Abstract:
Quantum mechanical oscillator synthesis and measurement using engineered couplings.
Quantum states exist in a Hilbert space and can
be described using an orthogonal set of basis
states. A common choice is to use the
eigenstates of the Hamiltonian, for which the
probability density doesn’t evolve in time.
These are convenient in experimental control,
because resonant pulses tuned to the energy
difference between states allow particular
transitions to be selected. However certain
advantages can be gained by working in an
alternative basis. I will describe recent
experimental work in which we perform control
of the oscillatory motion of a single trapped ion
to demonstrate state generation and control in
an “engineered” state basis, which we create by
controlling quantum interference pathways
between several resonant transitions which are
driven simultaneously [1]. This enables us to
create squeezed states of motion which are
preserved indefinitely using dissipation, and
enables novel measurements which provide a
simple verification for the created state. Using
additional unitary transformations, we
demonstrated novel quantum states in which
the atom is superposed at two well-separated
positions (commonly referred to as a
“Schrodinger’s cat” state), while having a
squeezed uncertainty in position [2].
Furthermore, we have demonstrated pure
oscillator cats for the first time in trapped-ions
using a post-selection technique, allowing us to
directly observe the interference between the
separated wavepackets. We achieve phase
space separations up to 15.6, which we are
forced to analyse in a squeezed Fock basis due
to the limitations of standard measurement
techniques. I will connect these methods to
work on scalable quantum information
processing with trapped ions.
[1] D. Kienzler et al. Science 347, 6217 (2015)
[2] H-Y. Lo et al. Nature 521, 336–339 (2015)