Sarah Mostame

Quantum simulator of an open quantum system using superconducting qubits: exciton transport in photosynthetic complexes

Open quantum system approaches are widely used in the description of physical, chemical and biological systems. A famous example is electronic excitation transfer in the initial stage of photosynthesis, where harvested energy is transferred with remarkably high efficiency to a reaction center. This transport is affected by the motion of a structured vibrational environment, which makes simulations on a classical computer very demanding. Here we propose an analog quantum simulator of complex open system dynamics with a precisely engineered quantum environment. Our setup is based on superconducting circuits, a well established technology. As an example, we demonstrate that it is feasible to simulate exciton transport in the Fenna–Matthews–Olson photosynthetic complex. Our approach allows for a controllable single-molecule simulation and the investigation of energy transfer pathways as well as non-Markovian noise-correlation effects.

Compressed Sensing for Multidimensional Spectroscopy Experiments

Compressed sensing is a processing method that significantly reduces the number of measurements needed to accurately resolve signals in many fields of science and engineering. We develop a two-dimensional variant of compressed sensing for multidimensional spectroscopy and apply it to experimental data. For the model system of atomic rubidium vapor, we find that compressed sensing provides an order-of-magnitude (about 10-fold) improvement in spectral resolution along each dimension, as compared to a conventional discrete Fourier transform, using the same data set. More attractive is that compressed sensing allows for random undersampling of the experimental data, down to less than 5% of the experimental data set, with essentially no loss in spectral resolution. We believe that by combining powerful resolution with ease of use, compressed sensing can be a powerful tool for the analysis and interpretation of ultrafast spectroscopy data.

General error estimate for adiabatic quantum computing

Most investigations devoted to the conditions for adiabatic quantum computing are based on the first-order correction

Quantum simulator for the Ising model with electrons floating on a helium film.

⟨{\ensuremath{\Psi}}_{\mathrm{ground}}(t)\ensuremath{\mid}\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{H}(t)\ensuremath{\mid}{\ensuremath{\Psi}}_{\mathrm{excited}}(t)⟩∕\mathrm{\ensuremath{\Delta}}{E}^{2}(t)⪡1

Efficient quantum circuits for diagonal unitaries without ancillas

. However, it is demonstrated that this first-order correction does not yield a good estimate for the computational error. Therefore, a more general criterion is proposed, which includes higher-order corrections as well, and shows that the computational error can be made exponentially small---which facilitates significantly shorter evolution times than the above first-order estimate in certain situations. Based on this criterion and rather general arguments and assumptions, it can be demonstrated that a run-time

Tunable nonequilibrium dynamics of field quenches in spin ice.

T

Quantum simulator for the O(3) nonlinear sigma model

of order of the inverse minimum energy gap

Linear-algebraic bath transformation for simulating complex open quantum systems

\mathrm{\ensuremath{\Delta}}{E}_{\mathrm{min}}

Decoherence in a dynamical quantum phase transition of the transverse Ising chain

is sufficient and necessary, i.e.,

Emulation of complex open quantum systems using superconducting qubits

T=O(\mathrm{\ensuremath{\Delta}}{E}_{\mathrm{min}}^{\ensuremath{-}1})