Qibosoq improvements

[JavierSerranoGarcia]

Hi @rodolfocarobene, we should work on some issues/improvements next week.

1. Allow declared channels at full speed, multiplexed and interpolated at the same experiment.
2. Move to PYNQ 3.0. I already created an SD card with it. Now we have to test it with qibosoq.
3. Improve the duration estimation of the calibration experiments.
4. Robustify qibosoq against small issues (buffer overflow, tproc not fast enough, running server,...) that happen "randomly".

and whatever we will come up with.

[rodolfocarobene]

Hi @JavierSerranoGarcia, thanks for the list!

Regarding (1), could you prepare some kind of notebook / example on how to use these channels with QICK (not qibosoq)? It would be very useful for me since I never used the interpolated channels

[JavierSerranoGarcia]

Hi @rodolfocarobene, as we talked last week we need to use ASAP the interpolated channel with qibosoq. Do you think you could do it in the weeks?

[rodolfocarobene]

Hi @JavierSerranoGarcia, yes I should be able to implement interpolated channels in this week (max the next one). But it would be really useful if you could share with me the working notebook you should me last week. I remember that I have to add the "mixer" parameter, but I am not sure where...

[JavierSerranoGarcia]

So @rodolfocarobene , here you are

from qick import *
from tqdm.notebook import tqdm

soc = QickSoc("../qick/firmware/qick_qibo_v2.bit")
soccfg = soc

# Setup configuration parameters
hw_cfg={"res_ch":6,
        "qubit_ch":9
       }
readout_cfg={
    "readout_length":soccfg.us2cycles(3.0, gen_ch=hw_cfg["res_ch"]), # [Clock ticks]
    "f_res": -200, # [MHz]
    "res_phase": 0,
    "adc_trig_offset": 175, # [Clock ticks]
    "res_gain":30000
    }
qubit_cfg={
    "sigma":soccfg.us2cycles(0.025, gen_ch=9),
    "pi_gain": 11500,
    "pi2_gain":11500//2, 
    "f_ge":4743.041802067813,
    "relax_delay":500
}
feedback_ch = 0 
mixer_f=7300

class SingleToneSpectroscopyProgram(AveragerProgram):
    def initialize(self):
        cfg=self.cfg   
        self.declare_gen(ch=cfg["res_ch"], nqz=2, mixer_freq=mixer_f, ro_ch=feedback_ch ) #Readout
        for ch in [feedback_ch]: #configure the readout lengths and downconversion frequencies
            self.declare_readout(ch=ch, length=cfg["readout_length"],
                                 freq=cfg["frequency"], gen_ch=cfg["res_ch"])

        freq=self.freq2reg(cfg["frequency"], gen_ch=cfg["res_ch"], ro_ch=feedback_ch)  # convert frequency to dac frequency (ensuring it is an available adc frequency)
        self.set_pulse_registers(ch=cfg["res_ch"], style="const", freq=freq, phase=0, gain=cfg["res_gain"],
                                length=cfg["readout_length"])

        self.synci(200)  # give processor some time to configure pulses

    def body(self):
        self.measure(pulse_ch=self.cfg["res_ch"], 
             adcs=[feedback_ch],
             adc_trig_offset=self.cfg["adc_trig_offset"],
             wait=True,
             syncdelay=self.us2cycles(self.cfg["relax_delay"])) 

expt_cfg={"reps":1000, "relax_delay":10,
          "start":7300-mixer_f, "step":1, "expts":200
         }
config={**hw_cfg,**readout_cfg,**qubit_cfg,**expt_cfg} #combine configs

fpts=expt_cfg["start"] + expt_cfg["step"]*np.arange(expt_cfg["expts"])

amps=[]
for f in tqdm(fpts):
    config["frequency"]=f

    rspec=SingleToneSpectroscopyProgram(soccfg, config)
    avgi,avgq=rspec.acquire(soc)
    amp=np.abs(avgi[0][0]+1j*avgq[0][0])
    amps.append(amp)
amps=np.array(amps)

plt.subplot(111,title="Resonator Spectroscopy", xlabel="Resonator Frequency (MHz)", ylabel="Amp. (adc level)")
plt.plot(fpts+mixer_f, amps,'o-')
max_freq=fpts[np.argmax(amps)]
plt.show()

[rodolfocarobene]

Thanks @JavierSerranoGarcia, I started to draft for supporting the interpolated channel.

However, I have some questions: from qibolab how do you want to specify the mixer frequency? Since it is not a standard parameter I see two options:

• Try to compute a good mixer frequency automatically, at the beginning of a sequence (and what for sweepers?)
• Fix in the platform.py a specific mixer_frequency for a specific channel

I have also other questions:

• in a sweeper, how would the interpolated channel behave? Is it possible to sweep its frequency or is it possible also to sweep the mixer_freq? Or maybe no sweeper is possible.
• Are there limits on the mixer frequency or on the frequency itself? I think that probably there is some limit on the frequency attribute

[JavierSerranoGarcia]

Hi @rodolfocarobene,

We should do the same as other instruments and set it in the platform (channel object) and in the runcard the parameter value port.lo_frequency.

The sweeper should sweep the frequency with a fixed mixer frequency. The interpolated channel frequencies must be between [-fs/2, fs/2] being fs in some channels 4915 and other 6881. So the bandwidth is quite large.

I am leaving on vacation for a couple of weeks so probably I will answer emails.