2 research outputs found
Efficient measurement of quantum dynamics via compressive sensing
The resources required to characterise the dynamics of engineered quantum
systems-such as quantum computers and quantum sensors-grow exponentially with
system size. Here we adapt techniques from compressive sensing to exponentially
reduce the experimental configurations required for quantum process tomography.
Our method is applicable to dynamical processes that are known to be
nearly-sparse in a certain basis and it can be implemented using only
single-body preparations and measurements. We perform efficient, high-fidelity
estimation of process matrices on an experiment attempting to implement a
photonic two-qubit logic-gate. The data base is obtained under various
decoherence strengths. We find that our technique is both accurate and noise
robust, thus removing a key roadblock to the development and scaling of quantum
technologies.Comment: New title and authors. A new experimental section. Significant
rewrite of the theor
Two-photon quantum walks in an elliptical direct-write waveguide array
Integrated optics provides an ideal test bed for the emulation of quantum
systems via continuous-time quantum walks. Here we study the evolution of
two-photon states in an elliptic array of waveguides. We characterise the
photonic chip via coherent-light tomography and use the results to predict
distinct differences between temporally indistinguishable and distinguishable
two-photon inputs which we then compare with experimental observations. Our
work highlights the feasibility for emulation of coherent quantum phenomena in
three-dimensional waveguide structures.Comment: 8 pages, 7 figure