1,832 research outputs found
Digital-Analog Quantum Simulations with Superconducting Circuits
Quantum simulations consist in the intentional reproduction of physical or
unphysical models into another more controllable quantum system. Beyond
establishing communication vessels between unconnected fields, they promise to
solve complex problems which may be considered as intractable for classical
computers. From a historic perspective, two independent approaches have been
pursued, namely, digital and analog quantum simulations. The former usually
provide universality and flexibility, while the latter allows for better
scalability. Here, we review recent literature merging both paradigms in the
context of superconducting circuits, yielding: digital-analog quantum
simulations. In this manner, we aim at getting the best of both approaches in
the most advanced quantum platform involving superconducting qubits and
microwave transmission lines. The discussed merge of quantum simulation
concepts, digital and analog, may open the possibility in the near future for
outperforming classical computers in relevant problems, enabling the reach of a
quantum advantage.Comment: Review article, 26 pages, 4 figure
Digital quantum simulators in a scalable architecture of hybrid spin-photon qubits
Resolving quantum many-body problems represents one of the greatest
challenges in physics and physical chemistry, due to the prohibitively large
computational resources that would be required by using classical computers. A
solution has been foreseen by directly simulating the time evolution through
sequences of quantum gates applied to arrays of qubits, i.e. by implementing a
digital quantum simulator. Superconducting circuits and resonators are emerging
as an extremely-promising platform for quantum computation architectures, but a
digital quantum simulator proposal that is straightforwardly scalable,
universal, and realizable with state-of-the-art technology is presently
lacking. Here we propose a viable scheme to implement a universal quantum
simulator with hybrid spin-photon qubits in an array of superconducting
resonators, which is intrinsically scalable and allows for local control. As
representative examples we consider the transverse-field Ising model, a spin-1
Hamiltonian, and the two-dimensional Hubbard model; for these, we numerically
simulate the scheme by including the main sources of decoherence. In addition,
we show how to circumvent the potentially harmful effects of inhomogeneous
broadening of the spin systems
Programming Quantum Computers Using Design Automation
Recent developments in quantum hardware indicate that systems featuring more
than 50 physical qubits are within reach. At this scale, classical simulation
will no longer be feasible and there is a possibility that such quantum devices
may outperform even classical supercomputers at certain tasks. With the rapid
growth of qubit numbers and coherence times comes the increasingly difficult
challenge of quantum program compilation. This entails the translation of a
high-level description of a quantum algorithm to hardware-specific low-level
operations which can be carried out by the quantum device. Some parts of the
calculation may still be performed manually due to the lack of efficient
methods. This, in turn, may lead to a design gap, which will prevent the
programming of a quantum computer. In this paper, we discuss the challenges in
fully-automatic quantum compilation. We motivate directions for future research
to tackle these challenges. Yet, with the algorithms and approaches that exist
today, we demonstrate how to automatically perform the quantum programming flow
from algorithm to a physical quantum computer for a simple algorithmic
benchmark, namely the hidden shift problem. We present and use two tool flows
which invoke RevKit. One which is based on ProjectQ and which targets the IBM
Quantum Experience or a local simulator, and one which is based on Microsoft's
quantum programming language Q.Comment: 10 pages, 10 figures. To appear in: Proceedings of Design, Automation
and Test in Europe (DATE 2018
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