Add sequences for Stark Shift-type experiments

QGL/BasicSequences/StarkShift.py

@@ -0,0 +1,167 @@
+from ..PulsePrimitives import *
+from ..Compiler import compile_to_hardware
+from ..ChannelLibraries import EdgeFactory
+from ..PulseSequencePlotter import plot_pulse_files
+from .helpers import create_cal_seqs, delay_descriptor, cal_descriptor
+import numpy as np
+from collections.abc import Iterable
+from itertools import product
+
+def StarkSpectroscopy(qubit, measurement, amplitude, 
+                            delay=200e-9, length=1e-6, showPlot=False):
+    """Stark shift spectroscopy experiment. Applies a coherent displacement
+        to the qubit readout cavity while doing pulsed spectroscopy.
+
+        Args:
+            qubit: Qubit channel to apply spectroscopy pulse to.
+
+            measurement: Measurement channel to apply displacement pulse to.
+
+            amplitude: Measurement pulse amplitude(s)
+
+            delay: Delay between end of spectroscopy pulse and start of MEAS(qubit).
+
+            length: Total length of cavity displacement pulse.
+
+        Returns:
+            metafile: Path to compiled sequence metafile.
+    """
+
+    if not isinstance(amplitude, Iterable):
+        amplitude = [amplitude]
+
+    def stark_shift_pulse(amp):
+        pump_pulse = Utheta(measurement, amp=amp, length=length)
+        l1 = length - delay - qubit.pulse_params["length"] - delay
+        spec_pulse = Id(qubit, length=l1)+X(qubit)+Id(qubit,length=delay)
+        return spec_pulse*pump_pulse
+
+    seqs = [[stark_shift_pulse(a), MEAS(qubit)] for a in amplitude]
+    axis_descriptor = {
+        'name': 'Stark Shift Amplitude',
+        'unit': None,
+        'points': list(amplitude),
+        'partition': 1
+    }
+    metafile = compile_to_hardware(seqs, 'StarkSpec/StarkSpec', axis_descriptor=axis_descriptor)
+
+    if showPlot:
+        plot_pulse_files(metafile)
+
+    return metafile
+
+def StarkEcho(qubit, measurement, amplitudes, delays, 
+                            wait=200e-9, periods=4, showPlot=False):
+    """Hahn echo sequence with a coherent displacement of the qubit measurement cavity.
+        Used to measure photon-induced dephasing. This sequence can cause a lot of cache pressure
+        so number of points may be limited.
+
+        TODO: Use QGL intrinsics to reduce sequence and memory cache utilization.
+
+        Args:
+            qubit: Qubit channel for Hahn echo.
+
+            measurement: Measurement channel of qubit.
+
+            amplitudes: Amplitude(s) of cavity displacement pulse. 
+
+            delays: Hahn echo delays - the t in 90-t-180-t-180. 
+
+            wait: Delay between end of cavity displacement pulse and start of MEAS(qubit).
+
+            periods: Number of artificial oscillations.
+
+        Returns:
+            metafile: Path to compiled sequence metafile.
+    """
+
+    if not isinstance(amplitudes, Iterable):
+        amplitudes = [amplitudes]
+
+    if not isinstance(delays, Iterable):
+        delays = [delays]
+
+    def echo_phase(n):
+        return 2*np.pi*periods/len(delays)*n
+
+    def echo_stark(n, amp, max_delay, meas_delay=200e-9):
+        x_len = qubit.pulse_params["length"]
+        max_len = 3*x_len + 2*max_delay + meas_delay
+        echo_wait = max_len - (3*x_len + 2*delays[n]) 
+
+        echo_seq = Id(qubit, echo_wait) + X90(qubit) + Id(qubit, delays[n]) + \
+                        Y(qubit) + Id(qubit, delays[n]) + U90(qubit, echo_phase(n))
+
+        meas_seq = Utheta(measurement, amp=amp, length=max_len)
+
+        return echo_seq*meas_seq
+
+
+    seqs = [[echo_stark(n, amp, np.max(delays)), Id(measurement, length=wait), MEAS(qubit)] 
+                for n, amp in product(range(len(delays)), amplitudes)]
+
+    axis_descriptor = [delay_descriptor(delays)] * len(amplitudes)
+
+    metafile = compile_to_hardware(seqs, 'StarkEcho/StarkEcho', axis_descriptor=axis_descriptor)
+
+    if showPlot:
+        plot_pulse_files(metafile)
+
+    return metafile
+
+
+def CavityPumpProbe(qubit, measurement, offsets, amplitude, 
+                            length=1e-6, wait=1e-6, showPlot=False):
+    """Time resolved cavity spectroscopy. Applies a coherent displacement to qubit
+        readout cavity while sweeping qubit spectroscopy pulse delay. Useful to measure
+        cavity kappa and cavity population.
+
+        Args:
+            qubit: Qubit channel for spectroscopy.
+
+            measurement: Measurement channel of qubit.
+
+            offsets: Spectroscopy pulse offset relative to start of cavity displacement pulse.
+
+            amplitude: Measurement pulse amplitude.
+
+            length: Total length of cavity displacement pulse.
+
+            wait: Delay between end of cavity displacement pulse and start of MEAS(qubit).
+
+        Returns:
+            metafile: Path to compiled sequence metafile.
+    """
+
+    if not isinstance(offsets, Iterable):
+        offsets = [offsets]
+
+    def cavity_probe(offset):
+        pump_pulse = Utheta(measurement, amp=amplitude, length=length)
+        x_len = qubit.pulse_params["length"]
+        if offset < -1*x_len:
+            return [X(qubit), Id(qubit, length=(-x_len-offset)), pump_pulse, Id(qubit, length=wait)]
+        elif offset < 0:
+            total_len = length-offset
+            pm = Id(measurement, length=offset)+pump_pulse
+            pq = X(qubit)+Id(qubit, length=(total_len-x_len))
+            return [pm*pq, Id(qubit, length=wait)]
+        elif offset < length:
+            pq = Id(qubit, length=offset)+X(qubit)+Id(qubit, length=(length-offset-x_len))
+            return [pump_pulse*pq, Id(qubit, length=wait)]
+        elif offset >= length:
+            assert offset < (length+wait), f"Wait time {wait} is too short!"
+            wait_len = wait - (offset-length+x_len)
+            return [pump_pulse, Id(qubit, length=(offset-length)), X(qubit), Id(qubit, length=wait_len)]
+
+    seqs = [[cavity_probe(off), MEAS(qubit)] for off in offsets]
+    axis_descriptor = delay_descriptor(offsets)
+    metafile = compile_to_hardware(seqs, 'CavityPumpProbe/CavityPumpProbe', axis_descriptor=axis_descriptor)
+
+    if showPlot:
+        plot_pulse_files(metafile)
+
+    return metafile
+
+
+

QGL/BasicSequences/__init__.py

@@ -8,3 +8,4 @@
 from .CR import EchoCRPhase, EchoCRLen, EchoCRAmp, PiRabi
 from .AllXY import AllXY
 from .Feedback import Reset, BitFlip3, MajorityVoteN
+from .StarkShift import StarkSpectroscopy, StarkEcho, CavityPumpProbe