What's the resolution of quadrature measurements?


I’m not entirely sure if this is the right place for this question. Take a Homodyne measurement of the position quadrature. Is there a ballpark figure for the resolution and range of measurements possible by the Xanadu X8 machine? i.e. If one was simulating the quadrature measurements, what would the appropriate bin size and range be for a real-world detector?


Hi @jange , welcome to the Forum!

This is indeed the place to ask. I don’t know the answer but I’ll ask someone in our team next week. :smiley:

Hi @jange,

My colleague Eli found the answer!

X8 only uses PNR measurements so there is no homodyne measurement for which to even define the resolution.

If you just want to know how to model a homodyne measurement in numerical simulations, you can model it in Strawberry Fields as a projection onto an extremely squeezed state basis. You can read more about that in the Strawberry Fields documentation for sf.ops.MeasureHomodyne.

I hope this helps!

Thank you very much!

Am I right to understand therefore that the sf.ops.MeasureHomodyne in the Gaussian backend accurately models this for the X8?

Hi @jange,

It’s actually the opposite. X8 does not use Homodyne measurements. Instead, MeasureFock() represents the photon-counting measurement that does indeed occur in X8.

Ah, I understand now. Thank you very much for all your help!

No problem, I’m glad I could help @jange !