algorithm

The perceval.algorithm package contains the code of several simple and generic quantum algorithms. It provides a Processor-centric syntax to run an algorithm locally or remotely, on a simulator or an actual QPU.

All algorithms take either a local or a remote processor as parameter, in order to perform a task. Processor runs simulations on a local computer while a RemoteProcessor turns Perceval into the client of a remote service such as Quandela Cloud, and the computation is performed remotely, on the selected platform.

However, for user experience, an algorithm has the same behavior be it run locally or remotely: every call to an algorithm command returns a Job object, hiding this complexity.

>>> from perceval import Processor, BasicState
>>> from perceval.algorithm import Sampler
>>> local_p = Processor("CliffordClifford2017", pcvl.BS())
>>> local_p.with_input(BasicState('|1,1>'))
>>> sampler = Sampler(local_p)
>>> local_sample_job = sampler.sample_count

Here, the computation has not started yet, but it’s been prepared in local_sample_job to run locally.

Samples of interest vs Shots

On a QPU, the acquisition is measured in shots. A shot is any coincidence with at least 1 detected photon. Shots act as credits on the Cloud services. Users have to set a maximum shots value they are willing to use for any given task.

>>> remote_p = pcvl.RemoteProcessor("sim:sampling")
>>> remote_p.set_circuit(pcvl.BS())
>>> remote_p.with_input(pcvl.BasicState('|1,1>'))
>>> sampler = pcvl.algorithm.Sampler(remote_p, max_shots_per_call=500_000)
>>> remote_sample_job = sampler.sample_count

Here, the computation was set-up to run on sim:sampling platform when remote_sample_job is executed.

For more information about the shots and shots/samples ratio estimate, please read Remote computing tutorial.