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BBN-Q / PyQLab

A python library for instrument control and superconducting QIP experiments.
Apache License 2.0
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RabiWidth giving a fatal cache controller error #20

Closed calebjordan closed 9 years ago

calebjordan commented 9 years ago

Compiling a pulse with

RabiWidth(q1, 1e-9*np.linspace(0, 1e3, 101), showPlot=True)

Leads to a red L2 on the APS producing the measurement pulse.

matthewware commented 9 years ago

What happens if you power cycle? Are you still using a 5 us pulse and 19 MHz SSB?

caryan commented 9 years ago

We're having trouble reproducing this issue. What firmware version are these APS2's running?

matthewware commented 9 years ago

If these are ones we programmed successfully the first time they should be flashed with v2.24 that came with the zipped v0.5 release. The one we had to redo is running a slightly newer version... v2.27 I think. My guess is 2.24. Is that right Caleb?

calebjordan commented 9 years ago

Power cycle revives the unit, problem happens again when we try to run the experiment. L1 flashes as normal, and then we get a solid green L1 and solid red L2. Still using a 5us pulse with a 19MHz SSB.

This one is running the v2.24 that Matt and I flashed, we haven't used the v2.27 one yet.

caryan commented 9 years ago

v2.27 has a bug so stick with v2.24 for now. I think you might be exceeding the waveform cache (128k samples) because the 19MHz autodyne frequency is not a nice multiple of 10ns. As an aside for measurement channels, the physical channel SSB frequency should be zero and the frequency should be set on the logical measurement channel.

Could you try a couple different approaches:

mattai1986 commented 9 years ago

Hi, Thanks for this suggestion. The RabiWidth sequence runs fine with a 10 MHz autodyne freq. However, we still have to set this freq under the SSB freq in the Physical tab of Channels. Setting the autodyne freq to 10 MHz in the logical tab and the SSB freq to zero leads to a baseband measurement pulse when I compile the sequence. I tried restarting the GUI as well as iphython and that had no effect.

mattai1986 commented 9 years ago

Ok, so changing autodyne freq does work now. Not sure what I did wrong the first few times.

Thanks.

matthewware commented 9 years ago

Do you remember what you did? I've seen this issue before where the autodyne frequency doesn't seem to have an effect.

caryan commented 9 years ago

Autodyne frequency is one of these ones that doesn't automagically update from the GUI to the notebook. There is work in progress to fix this. Already merged (e9f986ea986c20b991436cb6131ee9465b1f792f)

caryan commented 9 years ago

This will be fixed with the PREFETCH command but for now sequences must fit inside a single waveform cache of 128k samples. Error added in 3e9c74d07793c93d5df8788e3064f6ce68bec897