[minor] adding comments to and refactoring DirectConversionProtocol; …

…move the absorptive memory files to a new folder

example/Transducer_Examples/ConversionProtocols.py

@@ -13,13 +13,10 @@
 from sequence.components.memory import Memory
 from sequence.utils.encoding import fock
 import math
-from sequence.kernel.event import Event
-from sequence.kernel.process import Process
 import sequence.utils.log as log
-import matplotlib.pyplot as plt
 from sequence.components.transducer import Transducer
 from sequence.components.transmon import Transmon
-
+from sequence.constants import KET0, KET1
 
 from sequence.components.detector import Detector
 from sequence.components.photon import Photon   
@@ -28,9 +25,6 @@
 from qutip import Qobj
 
 
-ket1 = (0.0 + 0.0j, 1.0 + 0.0j) 
-ket0 = (1.0 + 0.0j, 0.0 + 0.0j) 
-
 MICROWAVE_WAVELENGTH = 999308 # nm
 OPTICAL_WAVELENGTH = 1550 # nm
 
@@ -44,12 +38,18 @@ def get_conversion_matrix(efficiency: float) -> Qobj:
     return Qobj(custom_gate_matrix, dims=[[4], [4]])
 
 
-
 class EmittingProtocol(Protocol):
     """Protocol for emission of single microwave photon by transmon.
+
+    Attributes:
+        owner (Node): the owner of this protocol, the protocol runs on the owner
+        name (str): the name of the protocol
+        tl (Timeline): the simulation timeline
+        transducer (Transducer): the transducer component
+        transmon (Transmon): the transmon component
     """
 
-    def __init__(self, owner: "Node", name: str, tl: "Timeline", transmon="Transmon", transducer="Transducer"):
+    def __init__(self, owner: "Node", name: str, tl: Timeline, transmon: Transmon, transducer: Transducer):
         super().__init__(owner, name)
         self.owner = owner
         self.name = name
@@ -61,7 +61,7 @@ def start(self) -> None:
 
         self.transmon.get()
 
-        if self.transmon.photons_quantum_state[0] == ket1:
+        if self.transmon.photons_quantum_state[0] == KET1:
             if random.random() < self.transmon.efficiency:
                 self.transmon._receivers[0].receive_photon_from_transmon(self.transmon.new_photon0) 
                 self.transmon.photon_counter += 1 
@@ -72,17 +72,23 @@ def start(self) -> None:
 
         print(f"Microwave photons emitted by the Transmon at Tx: {self.transmon.photon_counter}")
 
-
     def received_message(self, src: str, msg):
         pass
 
 
-
 class UpConversionProtocol(Protocol):
     """Protocol for Up-conversion of an input microwave photon into an output optical photon.
+
+    Attributes:
+        owner (Node): the owner of this protocol, the protocol runs on the owner
+        name (str): the name of the protocol
+        tl (Timeline): the simulation timeline
+        transducer (Transducer): the transducer component
+        node (Node): the receiver node (where DownConversionProtocol runs) -- NOTE this is an error! node's typing should be a str, instead of Node
+        transmon (Transmon): the transmon component
     """
 
-    def __init__(self, owner: "Node", name: str, tl: "Timeline", transducer: "Transducer", node: "Node", transmon: "Transmon"):
+    def __init__(self, owner: Node, name: str, tl: Timeline, transducer: Transducer, node: Node, transmon: Transmon):
         super().__init__(owner, name)
         self.owner = owner
         self.name = name
@@ -91,9 +97,16 @@ def __init__(self, owner: "Node", name: str, tl: "Timeline", transducer: "Transd
         self.transmon = transmon
         self.node = node
 
-    def start(self, photon: "Photon") -> None:
-        """start the protocol"""
-        if self.transducer.photon_counter > 0:
+    def start(self, photon: Photon) -> None:
+        """start the protocol  
+
+        NOTE (caitao, 12/21/2024): this start() method should be empty. 
+             The content of this function should be at a new convert() method that receives photons from the from the transducer
+
+        Args:
+            photon (Photon): photon from arrived at the transducer from the transmon
+        """
+        if self.transducer.photon_counter > 0:   # NOTE shouldn't use this photon_counter to determine
             custom_gate = get_conversion_matrix(self.transducer.efficiency)
 
             transmon_state_vector = np.array(self.transmon.input_quantum_state).reshape((4, 1))
@@ -106,7 +119,7 @@ def start(self, photon: "Photon") -> None:
 
             if random.random() < self.transducer.efficiency:
                 photon.wavelength = OPTICAL_WAVELENGTH
-                self.transducer._receivers[0].receive_photon(self.node, photon)
+                self.transducer._receivers[0].receive_photon(self.node, photon)  # NOTE the receiver should be the quantum channel
                 print("Successful up-conversion")
                 self.transducer.output_quantum_state = [0.0 + 0.0j, 0.0 + 0.0j, 1.0 + 0.0j, 0.0 + 0.0j]
                 print(f"State after successful up-conversion: {self.transducer.output_quantum_state}")
@@ -121,9 +134,14 @@ def received_message(self, src: str, msg):
         pass
 
 
-
 class DownConversionProtocol(Protocol):
     """Protocol for Down-conversion of an input optical photon into an output microwave photon.
+
+    Attributes:
+        owner (Node): the owner of this protocol, the protocol runs on the owner
+        name (str): the name of the protocol
+        tl (Timeline): the simulation timeline
+        transducer (Transducer): the transducer component
     """
 
     def __init__(self, owner: "Node", name: str, tl: "Timeline", transducer: "Transducer", transmon: "Transmon"):
@@ -134,10 +152,16 @@ def __init__(self, owner: "Node", name: str, tl: "Timeline", transducer: "Transd
         self.transducer = transducer
 
     def start(self, photon: "Photon") -> None:
-        """start the protocol"""
-        if self.transducer.photon_counter > 0:
-
-            transducer_state = [0.0 + 0.0j, 0.0 + 0.0j, 1.0 + 0.0j, 0.0 + 0.0j]
+        """start the protocol
+            
+            NOTE (caitao, 12/21/2024): this start() method should be empty. 
+                 The content of this function should be at a new convert() method that receives photons from the from the transducer
+        Args:
+            photon (Photon): the photon received at the transducer from the quantum channel
+        """
+        if self.transducer.photon_counter > 0:   # NOTE shouldn't use this photon_counter to determine
+
+            transducer_state = [0.0 + 0.0j, 0.0 + 0.0j, 1.0 + 0.0j, 0.0 + 0.0j]  # NOTE Why is this the transducer's state 
             custom_gate = get_conversion_matrix(self.transducer.efficiency)
 
             transducer_state_vector = np.array(transducer_state).reshape((4, 1))
@@ -164,6 +188,3 @@ def start(self, photon: "Photon") -> None:
     def received_message(self, src: str, msg):
         pass
 
-
-
-

example/Transducer_Examples/DirectConversion.py

@@ -2,7 +2,6 @@
 sys.path.append('.')
 
 import numpy as np
-import sequence.utils.log as log
 import matplotlib.pyplot as plt
 
 from sequence.kernel.timeline import Timeline
@@ -14,6 +13,7 @@
 from sequence.components.transmon import Transmon
 from sequence.components.transducer import Transducer
 from sequence.components.detector import FockDetector
+from sequence.constants import KET0, KET1
 
 from example.Transducer_Examples.ConversionProtocols import EmittingProtocol
 from example.Transducer_Examples.ConversionProtocols import UpConversionProtocol
@@ -26,24 +26,20 @@
 FREQUENCY = 1e9
 MICROWAVE_WAVELENGTH = 999308 # nm
 OPTICAL_WAVELENGTH = 1550 # nm
-MEAN_PHOTON_NUM=1
 
 # Timeline
 START_TIME = 0
 EMISSION_DURATION = 10 # ps
 CONVERSION_DURATION = 10 # ps
 PERIOD = EMISSION_DURATION + CONVERSION_DURATION + CONVERSION_DURATION
 
-# Transmon
-ket0 = (1.0 + 0.0j, 0.0 + 0.0j) 
-ket1 = (0.0 + 0.0j, 1.0 + 0.0j) 
 
-state_list= [ket1, ket0] 
+state_list= [KET1, KET0] 
 TRANSMON_EFFICIENCY = 1
 
 # Transducer
-EFFICIENCY_UP   = 0.5
-EFFICIENCY_DOWN = 0.5
+EFFICIENCY_UP   = 0.6
+EFFICIENCY_DOWN = 0.6
 
 # Fock Detector
 MICROWAVE_DETECTOR_EFFICIENCY_Rx = 1
@@ -54,6 +50,7 @@
 ATTENUATION = 0
 DISTANCE = 1e3
 
+
 class Counter:
     def __init__(self):
         self.count = 0
@@ -62,7 +59,7 @@ def trigger(self, detector, info):
         self.count += 1
 
 
-#NODES OF THE NETWORK 
+# NODES OF THE NETWORK 
 
 
 class SenderNode(Node):
@@ -75,23 +72,27 @@ class SenderNode(Node):
         timeline (Timeline): timeline
         transmon_name (str): name of the transmon
         detector_name (str): name of the detector
+        counter2 (Counter):  the counter for the detector
         transducer_name (str): name of the transducer
-
+        counter (Counter):   the counter for the transducer
+        emitting_protocol (EmittingProtocol): the protocol for emitting photons
+        upconversion_protocol (UpConversionProtocol): the protocol for up converting the microwave to optical photon
     """
     def __init__(self, name, timeline, node2):
         super().__init__(name, timeline)
 
         # transmon
         self.transmon_name = name + ".transmon"
-        transmon = Transmon(name=self.transmon_name, owner=self, timeline=timeline, wavelengths=[MICROWAVE_WAVELENGTH, OPTICAL_WAVELENGTH], photon_counter=0, efficiency=TRANSMON_EFFICIENCY, photons_quantum_state= state_list)
+        transmon = Transmon(name=self.transmon_name, owner=self, timeline=timeline, wavelengths=[MICROWAVE_WAVELENGTH, OPTICAL_WAVELENGTH], \
+                            photon_counter=0, efficiency=TRANSMON_EFFICIENCY, photons_quantum_state=state_list)
         self.add_component(transmon)
 
         # detector
         detector_name = name + ".fockdetector"
         detector = FockDetector(detector_name, timeline, wavelength=MICROWAVE_WAVELENGTH, efficiency=MICROWAVE_DETECTOR_EFFICIENCY_Tx)
         self.add_component(detector)
-        self.counter = Counter()
-        detector.attach(self.counter)
+        self.counter2 = Counter()
+        detector.attach(self.counter2)
 
         # transducer
         self.transducer_name = name + ".transducer"
@@ -110,7 +111,6 @@ def __init__(self, name, timeline, node2):
         self.upconversion_protocol = UpConversionProtocol(self, name + ".upconversion_protocol", timeline, transducer, node2, transmon)
 
 
-
 class ReceiverNode(Node):
     """Receiver node in the Direct Conversion Protocol. 
     
@@ -136,7 +136,8 @@ def __init__(self, name, timeline):
         self.counter = Counter()
 
         # transmon
-        transmon = Transmon(name=self.transmon_name, owner=self, timeline=timeline, wavelengths=[MICROWAVE_WAVELENGTH, OPTICAL_WAVELENGTH], photons_quantum_state=state_list, photon_counter=0, efficiency=1)
+        transmon = Transmon(name=self.transmon_name, owner=self, timeline=timeline, wavelengths=[MICROWAVE_WAVELENGTH, OPTICAL_WAVELENGTH], \
+                            photons_quantum_state=state_list, photon_counter=0, efficiency=1)
         self.add_component(transmon)
 
         # fock detector
@@ -155,12 +156,11 @@ def __init__(self, name, timeline):
         # down conversion protocol
         self.downconversion_protocol = DownConversionProtocol(self, name + ".downconversion_protocol", timeline, transducer, transmon)
 
-
     def receive_photon(self, src, photon):
         self.components[self.transducer_name].receive_photon_from_channel(photon)
 
 
-#MAIN
+# MAIN
 
 if __name__ == "__main__":
 
@@ -170,7 +170,7 @@ def receive_photon(self, src, photon):
     node2 = ReceiverNode("node2", tl)
     node1 = SenderNode("node1", tl, node2)
 
-    qc1 = QuantumChannel("qc.node1.node2", tl, attenuation=ATTENUATION, distance=DISTANCE)
+    qc1 = QuantumChannel("qc.node1.node2", tl, attenuation=ATTENUATION, distance=DISTANCE)  # NOTE: this quantum channel is not used
     qc1.set_ends(node1, node2.name)
 
     if EFFICIENCY_UP >= 0 and EFFICIENCY_UP <= 1 and EFFICIENCY_DOWN >= 0 and EFFICIENCY_DOWN <= 1:
@@ -205,14 +205,14 @@ def receive_photon(self, src, photon):
     detector2   = node2.get_components_by_type("FockDetector")[0]
 
     print(f"--------------------")
-    print(f"Direct Quantum Transduction Protocol starts, the qubit that we are going to convert is: {ket1}")
+    print(f"Direct Quantum Transduction Protocol starts, the qubit that we are going to convert is: {KET1}")
 
     for trial in range(NUM_TRIALS): 
 
         print(f"--------------------")
         print(f"Trial {trial}:")
 
-        # reset timeline
+        # reset timeline   # NOTE should not reset timeline, instead, each experiment should keep running for some time.
         tl.time = 0
         tl.init()
 
@@ -224,17 +224,17 @@ def receive_photon(self, src, photon):
         transducer2.photon_counter = 0
         detector2.photon_counter   = 0
 
-        process0 = Process(node1.emitting_protocol, "start", [])
+        process0 = Process(node1.emitting_protocol, "start", [])  # NOTE: there should only be one event to kick the simulation (following 2 events shouldn't exist here)
         event_time0 = (cumulative_time + EMISSION_DURATION) 
         event0 = Event(event_time0, process0)
         tl.schedule(event0)
-    
-        process1 = Process(node1.upconversion_protocol, "start", [Photon]) 
+
+        process1 = Process(node1.upconversion_protocol, "start", [Photon])    # NOTE: class Photon shouldn't be the parameter, it should be Photon object
         event_time1 = (event_time0 + CONVERSION_DURATION) 
         event1 = Event(event_time1, process1)
         tl.schedule(event1)
 
-        process2 = Process(node2.downconversion_protocol, "start", [Photon])
+        process2 = Process(node2.downconversion_protocol, "start", [Photon])  # NOTE: class Photon shouldn't be the parameter, it should be Photon object
         event_time2 =(event_time1 + CONVERSION_DURATION) 
         event2 = Event(event_time2, process2)
         tl.schedule(event2)
@@ -257,7 +257,6 @@ def receive_photon(self, src, photon):
         converted_photons.append(total_photons_successful)
 
 
-
     # RESULTS
 
     print(f"- - - - - - - - - -")

sequence/components/photon.py

@@ -4,7 +4,7 @@
 Photons may be encoded directly with polarization or time bin schemes, or may herald the encoded state of single atom memories.
 """
 from typing import Dict, Any, List, Union, TYPE_CHECKING
-from numpy import log2
+from numpy import log2, ndarray
 
 if TYPE_CHECKING:
     from numpy.random._generator import Generator
@@ -15,6 +15,7 @@
 from ..components.circuit import Circuit
 from ..utils.encoding import polarization
 from ..kernel.quantum_state import FreeQuantumState
+from ..constants import EPSILON
 
 
 class Photon:
@@ -43,8 +44,7 @@ class Photon:
     _measure_circuit = Circuit(1)
     _measure_circuit.measure(0)
 
-    def __init__(self, name: str, timeline: "Timeline", wavelength=0, location=None, encoding_type=polarization,
-                 quantum_state=None, use_qm=False):
+    def __init__(self, name: str, timeline: "Timeline", wavelength=0, location=None, encoding_type=polarization, quantum_state=None, use_qm=False):
         """Constructor for the photon class.
 
         Args:
@@ -84,8 +84,8 @@ def __init__(self, name: str, timeline: "Timeline", wavelength=0, location=None,
                 quantum_state = (complex(1), complex(0))
             else:
                 assert type(quantum_state) is tuple
-                assert all([abs(a) <= 1.01 for a in quantum_state]), "Illegal value with abs > 1 in photon state"
-                assert abs(sum([abs(a) ** 2 for a in quantum_state]) - 1) < 1e-5, "Squared amplitudes do not sum to 1"
+                assert all([abs(a) < 1 + EPSILON for a in quantum_state]), "Illegal value with abs > 1 in photon state"
+                assert abs(sum([abs(a) ** 2 for a in quantum_state]) - 1) < EPSILON, "Squared amplitudes do not sum to 1"
                 num_qubits = log2(len(quantum_state))
                 assert num_qubits == 1, "Length of amplitudes for single photon should be 2"
             self.quantum_state = FreeQuantumState()

sequence/components/transducer.py

@@ -43,7 +43,8 @@ def add_output(self, outputs: List):
             self.add_receiver(i)
 
     def receive_photon_from_transmon(self, photon: "Photon") -> None:
-        self.photon_counter += 1 
+        """Receive a photon from the transmon"""
+        self.photon_counter += 1 # NOTE should schedule an UpConvert event in the future and pass on the argument photon to the UpConverion protocol's convert() method
 
     def receive_photon_from_channel(self, photon: "Photon") -> None:
         self.photon_counter += 1