BBQ Simulation data

Cavity transmission(port8, port 6) vs empty network transmission(port 14)
output port: 3 (low frequency output)

RI-1 Cavity (IF BW: 100 Hz, # of avg.: 5)

Cavity attenuation + Eccosorb filter attenuation = 96.7882 dB

Cavity attenuation + Eccosorb filter attenuation = 58.1088 dB

RI-2 Cavity (IF BW: 500 Hz, # of avg.: 2)

Cavity attenuation + Eccosorb filter attenuation = 101.5438 dB

Cavity attenuation + Eccosorb filter attenuation = 71.5471 dB

Data location:
RI-2 transmission: D:\redmine\runs\DR1_run_7\Labber\Data\2020\10\Data_1011\RI-2_CW_TM010_longer_antenna.hdf5
RI-1 transmission: D:\redmine\runs\DR1_run_7\Labber\Data\2020\10\Data_1012\RI-1_CW_TM010_longer_antenna.hdf5
empty transmission: D:\redmine\runs\DR1_run_7\Labber\Data\2020\10\Data_1017\Empty_network_reference.hdf5
empty transmission: D:\redmine\runs\DR1_run_7\Labber\Data\2020\10\Data_1017\Empty_network_reference_2.hdf5

Cavity transmission test
Cavity transmission(port8, port 6) vs empty network transmission(port 14)
output port: 3 (low frequency output)¶

Used same settings for all measurements
IF BW: 50 Hz
number of avg.: 2
sweep span: 10 kHz
number of points: 10k

RI-1

Cavity + Ecco. filter attenuation:
on-resonance: 64.10917 dB
off-resonance: 90.8040 dB¶

Cavity + Ecco. filter attenuation:
on-resonance: 37.879022 dB
off-resonance: 68.2002 dB

Cavity + Ecco. filter attenuation:
on-resonance: 13.13005 dB
off-resonance: 27.748385 dB

RI-2¶

Cavity + Ecco. filter attenuation:
on-resonance: 38.639995 dB
off-resonance: 88.831209 dB

Cavity + Ecco. filter attenuation:
on-resonance: 29.17232 dB
off-resonance: 68.679998 dB

Cavity + Ecco. filter attenuation:
on-resonance: 15.762697 dB
off-resonance: 28.31977 dB

Data location:
RI-2 transmission: D:\redmine\runs\DR1_run_7\Labber\Data\2020\10\Data_1019\Transmisiosn_test_RI2_reson_2.hdf5
RI-1 transmission: D:\redmine\runs\DR1_run_7\Labber\Data\2020\10\Data_1019\Transmisiosn_test_RI1_reson_2.hdf5
empty transmission: D:\redmine\runs\DR1_run_7\Labber\Data\2020\10\Data_1019\Transmisiosn_test_empty_RI1_reson.hdf5
empty transmission: D:\redmine\runs\DR1_run_7\Labber\Data\2020\10\Data_1019\Transmisiosn_test_empty_RI2_reson.hdf5

Cross-Kerr effect?¶

D:\redmine\runs\DR1_run_7\Labber\Data\2020\10\Data_1022\RI-1_CW_TM010_dispersive_shift_wide_range.hdf5

D:\redmine\runs\DR1_run_7\Labber\Data\2020\10\Data_1023\RI-1_CW_TM010_dispersive_shift_ge_3.hdf5

Cavity: RI-1
Readout mode: TM010
CW measurement with CW qubit drive

Measured dispersive shift-like shift(~300 Hz). But it turned out that the shifts occur at cavity mode, not at qubit mode(This was confirmed by measuring peaks with VNA without qubit drive).
This could be the cross-Kerr effect between cavity modes. (qubit mediates cavity-cavity interaction)
Cross-Kerr shift is very small(~200 Hz) because cavity mode inherits very small anharmonicity from the qubit, so cavity-cavity coupling is small whereas qubit-cavity coupling is relatively big(100kHz-MHz).

If this is truly cross-Kerr effect, it means qubit is alive and it was already in the low-power regime from the beginning.

Will do more scanning through the weekend to see qubit mode.

List of RI-1 cavity modes at 7-8 GHz¶

These are all measured with VNA at power -20 dBm and 0 dBm

7.063609566 GHz
7.064449474 GHz
7.184211502 GHz
7.397523311 GHz
7.399844343 GHz
7.601104091 GHz
7.63045704 GHz
7.656426794 GHz
7.685847298 GHz
7.691494555 GHz
7.825142061 GHz
7.829159502 GHz
7.830613116 GHz
7.983 GHz

Tuned 3 GHz JPA From Pappas. Gain is +16 dB.
bias: 822 uA
Pump 2.999GHz; -19.93 dBm

RI-1 cavity two-tone cross-Kerr scanning(3-13.5 GHz) result¶

Tone 1: Weak(-40dBm) prove tone by VNA sweeping around the readout mode(7.601 GHz)
Tone 2: High power(18dBm) scanning tone by VSG

VNA scan: # of avg = 2, IF BW=3 kHz, # of points=50.

I found 49 cross-Kerrs and most of them are cavity modes.
See attached PDF file.

I found two interesting shifts.
They showed shift in two-tone scan, but there was no cavity mode at that frequency.

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0104\RI-1_CW_7.601_cross-Kerr_scan(2-18dBm)(10.595-10.894GHz)_3.hdf5

There is a cross-Kerr at 10.806 GHz.

If we see through single tone VNA scan, we can find a notch at that frequency.

D:\redmine\runs\DR1_run_7\Labber\Data\2020\12\Data_1231\RI-1_CW_10.806_spectroscopy.hdf5

Why notch??

If we increase power, then we see some other shifts.

And those shifts does not show any cavity resonance at that frequencies.
So they can be qubit effect. Not cross Kerr.

Need Rabi experiment to confirm that those are truly qubit effects.

Result:

10.8 GHz seems not a qubit.¶

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0108\Ri-1_KPulsed_7.601_cross-Kerr_scan(5dBm)(10.76-10.83)_11.hdf5

There are some small oscillatory response, but it looks more like noise than Rabi.

I also did fine qubit scanning up to 18 GHz, but no qubit signal found.
I will return to self-Kerr fitting with VNA.

Pappas 2D Qubit Calibrations¶

1. Readout resonator spectroscopy¶

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0122\Pappas_KPulsed_readout_scan_2.hdf5

Readout frequency(qubit: ground): 6.48473 GHz

2. Qubit spectroscopy¶

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0123\Pappas_KPulsed_Chevron.hdf5

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0122\Pappas_KPulsed_qubit_scan_3.hdf5

Qubit frequency(f01): 5.53895 GHz
f02/2: 5.407204 GHz
Qubit anharmonicity(alpha): 263.492 MHz

3. Pi-pulse calibration¶

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0124\Pappas_KPulsed_Rabi.hdf5

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0124\Pappas_KPulsed_pi-pulse-calibrate_3.hdf5
Qubit VSG power: -10 dBm
AWG amplitude: 670 mV
pi-pulse length: 57 ns

4. Dispersive coupling(chi) measurement

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0124\Pappas_KPulsed_chi_calibrate.hdf5¶

Dispersive coupling: 2.272 MHz

T1 measurement¶

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0124\Pappas_KPulsed_T1.hdf5

T1: 3 microsecond

I will continue T2 measurement, and thermal photon number calibrations.

Pappas 2D Qubit Calibrations 2¶

We found higher level transitions: f02/2, f12.

1. f02/2 transition¶

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0126\Pappas_KPulsed_f02over2(no_side_band).hdf5
The f02/2 spectroscopy

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0126\Pappas_KPulsed_f02-over-2_Chevron.hdf5
The Chevron plot of f02/2 Rabi oscillations

f02/2 frequency: 5.407381 GHz
qubit VSG power: 0dBm
qubit AWG amplitude: 1V

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0127\Pappas_KPulsed_f02_chi_measurement.hdf5
The readout resonator spectroscopy when we send the pi-pulse of f02/2.
There is residual ground state population after the f02/2 pi-pulse. Seems like the pi-pulse is not fully calibrated enough. Or the f02/2 transition is second order transition, the transition probability is much lower than f01 transition, making it hard to fully rotate the state?

f12 transition¶

From the information from f02/2, we can estimate f12.

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0127\Pappas_KPulsed_f12(no_side_band)_2.hdf5

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0127\Pappas_KPulsed_f12_Chevron_2.hdf5

Now we can precisely measure f12.

f12 frequency: 5.2792 GHz
qubit VSG power: 0 dBm
qubit AWG amplitude: 1V
qubit anharmonicity: f01-f12 = 259.75 MHz

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0127\Pappas_KPulsed_f12_Rabi_2.hdf5

Now, using this paper(https://rsl.yale.edu/sites/default/files/demonstrating_a_driven_reset_2013.pdf), we will implement reset protocol to eliminate the thermal excitations and reset the qubit into the ground state.

Thermal photon population measurement by Rabi Population Measurement(RPM)¶

We implemented RPM driver that estimates the thermal photons at the qubit.
The idea is based on the paper(https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.110.120501).

By comparing the two oscillation amplitudes, we can estimate the thermal photon population.

The estimated Pe = 0.271591.

We can estimate the effective qubit temperature based on Boltzmann statistics.

T_eff = 269.45 mK

This was an initial trial.
I will do a more precise measurement tomorrow.

Pappas 2D qubit, T2 measurement¶

D:\redmine\runs\DR1_run_7\Labber\Data\2021\01\Data_0130\Pappas_KPulsed_Ramsey.hdf5