2,555 research outputs found
Quantum localization bounds Trotter errors in digital quantum simulation
A fundamental challenge in digital quantum simulation (DQS) is the control of an inherent error, which appears when discretizing the time evolution of a quantum many-body system as a sequence of quantum gates, called Trotterization. Here, we show that quantum localization-by constraining the time evolution through quantum interference-strongly bounds these errors for local observables, leading to an error independent of system size and simulation time. DQS is thus intrinsically much more robust than suggested by known error bounds on the global many-body wave function. This robustness is characterized by a sharp threshold as a function of the Trotter step size, which separates a localized region with controllable Trotter errors from a quantum chaotic regime. Our findings show that DQS with comparatively large Trotter steps can retain controlled errors for local observables. It is thus possible to reduce the number of gate operations required to represent the desired time evolution faithfully
Evaluation of the users value of salts against apple scab and powdery mildew for fruit production
The research was aimed at finding anti resistance strategies for Integrated fruit growing.
As the salts tested may be approvable for organic farming, the trial results are also of
value for the development of scab an mildew control strategies for organic fruit growing. As
new fungicides are mainly unisite action fungicides, the problem of fungicide resistance
development is becoming more important every year. Combining chemical fungicides,
which is the best anti-resistance strategy, is not always possible or recommended in the
case when the number of available chemical fungicides are limited or a reduction in
fungicide use is asked for. Therefore the use of salts as an anti-resistance strategy was
looked upon. The salts evaluated were K(HCO3), KH2PO3, KHPO4 and K2SiO3. When
using these salts as an anti-resistance strategy the efficacy obtained when spraying the
compounds alone was often to low to be used in rotation with chemical fungicides. Only
with K(HCO3)2 a good efficacy can be observed in some years. The variation in efficacy
with K(HCO3)2 observed is higher for powdery mildew. K(HCO3)2 can be considered as a
ideal product for scab control in organic orchards at moments of low infection risk
Quantum simulation of lattice gauge theories using Wilson fermions
Quantum simulators have the exciting prospect of giving access to real-time
dynamics of lattice gauge theories, in particular in regimes that are difficult
to compute on classical computers. Future progress towards scalable quantum
simulation of lattice gauge theories, however, hinges crucially on the
efficient use of experimental resources. As we argue in this work, due to the
fundamental non-uniqueness of discretizing the relativistic Dirac Hamiltonian,
the lattice representation of gauge theories allows for an optimization that up
to now has been left unexplored. We exemplify our discussion with lattice
quantum electrodynamics in two-dimensional space-time, where we show that the
formulation through Wilson fermions provides several advantages over the
previously considered staggered fermions. Notably, it enables a strongly
simplified optical lattice setup and it reduces the number of degrees of
freedom required to simulate dynamical gauge fields. Exploiting the optimal
representation, we propose an experiment based on a mixture of ultracold atoms
trapped in a tilted optical lattice. Using numerical benchmark simulations, we
demonstrate that a state-of-the-art quantum simulator may access the Schwinger
mechanism and map out its non-perturbative onset.Comment: 19 pages, 11 figure
Quantum control of spin-correlations in ultracold lattice gases
We demonstrate that it is possible to prepare a lattice gas of ultracold
atoms with a desired non-classical spin-correlation function using atom-light
interaction of the kind routinely employed in quantum spin polarization
spectroscopy. Our method is based on quantum non-demolition (QND) measurement
and feedback, and allows in particular to create on demand exponentially or
algebraically decaying correlations, as well as a certain degree of
multi-partite entanglement.Comment: 2 figure
- …