669 research outputs found
Steady shocks around black holes produced by sub-keplerian flows with negative energy
We discuss a special case of formation of axisymmetric shocks in the
accretion flow of ideal gas onto a Schwarzschild black hole: when the total
energy of the flow is negative. The result of our analysis enlarges the
parameter space for which these steady shocks are exhibited in the accretion of
gas rotating around relativistic stellar objects. Since keplerian disks have
negative total energy, we guess that, in this energy range, the production of
the shock phenomenon might be easier than in the case of positive energy. So
our outcome reinforces the view that sub-keplerian flows of matter may
significantly affect the physics of the high energy radiation emission from
black hole candidates. We give a simple procedure to obtain analytically the
position of the shocks. The comparison of the analytical results with the data
of 1D and 2D axisymmetric numerical simulations confirms that the shocks form
and are stable.Comment: 5 pages, 5 figures, accepted by MNRAS on 10 November 200
Quantum Gate Pattern Recognition and Circuit Optimization for Scientific Applications
There is no unique way to encode a quantum algorithm into a quantum circuit.
With limited qubit counts, connectivities, and coherence times, circuit
optimization is essential to make the best use of near-term quantum devices. We
introduce two separate ideas for circuit optimization and combine them in a
multi-tiered quantum circuit optimization protocol called AQCEL. The first
ingredient is a technique to recognize repeated patterns of quantum gates,
opening up the possibility of future hardware co-optimization. The second
ingredient is an approach to reduce circuit complexity by identifying zero- or
low-amplitude computational basis states and redundant gates. As a
demonstration, AQCEL is deployed on an iterative and efficient quantum
algorithm designed to model final state radiation in high energy physics. For
this algorithm, our optimization scheme brings a significant reduction in the
gate count without losing any accuracy compared to the original circuit.
Additionally, we have investigated whether this can be demonstrated on a
quantum computer using polynomial resources. Our technique is generic and can
be useful for a wide variety of quantum algorithms.Comment: 22 pages, 16 figure
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