c4-sw_sample cannot be accessed without QPU time

I am trying to use the c4-sw_sample solver to simulate what the QPU response would be like without using any QPU access time. However, when running the code:

sampler = DWaveSampler(token = 'mytoken', solver='c4-sw_sample')


The code prints out a conversion rate of 1. Is this intentional? It seems weird to me to charge the same amount of quota time for a software simulation as hitting a hardware QPU. Just seemed odd so wanted to shed some light in case that shouldn't be the case.




  • Hello,

    This is actually a typo.

    The c4 solver doesn't charge any time.
    It was just added to the properties by mistake.

    Thank you for pointing this out!

    We are looking into fixing this.

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  • Thanks David! Glad I could help. Do you know if there are any plans to extend this to a larger Chimera size?

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  • I don't believe so. 
    Software solvers are heavy on resources, so making them larger becomes impractical very quickly, due to the exponential growth of the problem.

    For testing out ideas, a SimulatedAnnealingSampler for example can also be helpful, although the results might vary:

    I hope this is helpful!

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  • That's what I was afraid of. I've used Simulated Annealing in the past to debug but wanted to more simulate the properties of the actual QPU, so I did not have to worry about eating into my QPU quota. Thanks for the help!

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