Added documentation on the GENswitch, QBox, Windfreak MWS and IQ modu…

…lation in general.

README.md

@@ -7,6 +7,9 @@ This is a toolbox to control instruments to run a general lab experiments. This
 There are two classes of documentation provided for this stack:
 
 - [User documentation](docs/User/Readme.md)
+    - [Driver-specific documentation](docs/User/InstrumentSpecific/Readme.md)
+    - [Custom device documentation](docs/User/CustomDevices/Readme.md)
+    - [Measurement methods](docs/User/MeasurementMethods/Readme.md)
 - [Developer documentation](docs/Developer/Readme.md)
 
 

docs/User/CustomDevices/BoxIQmod.md

@@ -0,0 +1,45 @@
+# Qubit Control and Readout Box (IQ modulation)
+
+This is a compact **1U rack-mount module** that enables qubit readout and control (with in-situ mixer calibration). The layout is as follows:
+
+![My Diagram3](BoxIQmod.drawio.svg)
+
+The front panel consists of all SMA ports except the two DC ports which are BNC. The general usage notes will be highlighted in the sections below.
+
+## Readout
+
+The box uses a heterodyne scheme for the readout. The idea is that:
+
+- The readout resonator is excited (directly into the fridge input outside the box) at the resonant frequency $f_0$.
+- The output from the fridge looks like $A\cos(2\pi f_0 t + \varphi)$ where the goal is to find $I=A\cos(\varphi)$ and $Q=A\sin(\varphi)$.
+- The LO downconversion source is set to $f_0+f_{off}$ (can be any frequency offset, but it is convenient to typically use $f_{off}=25~\textnormal{MHz}$). Useful to utilise [`VariableSpaced`](../Var_Defns.md).
+- The *Marki MLIQ0218L* is a wide-band mixer that can operate over 2-18GHz and thus, covers the usual 6.9-12GHz resonator range. It embeds the amplitude and phase of the readout output from the fridge onto the signal: $A\cos(2\pi f_{off}t+\varphi)$.
+- The signal is subsequently filtered for aliases and amplified before sending into the ADC digitiser where the signal is digitally demodulated and filtered to extract the I and Q components (either in the [CPU](../Proc_CPU_list.md#cpu-ddc)/[GPU](../Proc_GPU_list.md#gpu-ddc) or onboard any [FPGA](../Proc_FPGA_list.md#fpga-ddc) processors).
+
+The advantages of this method are:
+
+- No filters or IQ-modulators are required (as with a homodyne upconversion setup where the second sideband requires elimination).
+- Only one digitiser input is required (as opposed to two if downconverting exactly to DC when using $f_0$ for the LO).
+
+## Qubit control and mixer calibration
+
+The qubit is controlled via [IQ modulation](../MeasurementMethods/IQmod.md) via the two AWG ports and the MW LO port. The mixer DC offsets are controlled via the two DC BNC ports (feeding into Bias-Ts). The *Marki MLIQ0218L* was once again chosen for its wide-band operation (albeit, the splitter it to 4-12GHz qubit frequency operation). 
+
+To perform mixer calibration, the *RADIALL R570432100* switch is set to port 1 to sniff the signal sent directly to the fridge. This signal is sent to the downconversion readout setup. That is:
+
+- The downconversion LO is set to $f_{in}+f_{off}$ and the digital demodulation is done on $f_{off}$.
+- This effectively makes the readout setup a spectrum analyser where the manitude of any peak at $f_{in}$ can be sampled.
+- By sweeping the value of $f_{in}+f_{off}$ on the downconversion LO source, one may sample the magnitudes of the sideband and LO peaks.
+
+The panel LED lights up to indicate that the switch is on mixer calibration mode. To use the switch, simply instantiate the [HAL](../GENswitch.md) over the driver YAML:
+
+```yaml
+  sw_qbox:
+    type: sqdtoolz.Drivers.SW_RpiIQBox.SW_RpiIQBox
+    address: 'TCPIP::192.168.1.19::4000::SOCKET'
+    parameters:
+      pulse_delay_time:
+        initial_value: 1
+```
+
+Just change the IP address of the Raspberry Pi (with the [drivers](https://github.com/sqdlab/SQDdevRPi) installed) as appropriate. The switch states are given as `'Pmix'` and `'Pmeas'` for mixer calibration and normal readout measurements respectively.

docs/User/CustomDevices/Readme.md

@@ -0,0 +1,6 @@
+# Custom devices
+
+Here is a list of custom devices that aid in measurements as supported by *SQDToolz*:
+
+- [Qubit Control and Readout Box (IQ modulation)](BoxIQmod.md)
+

docs/User/GENmwSource.md

@@ -9,6 +9,7 @@ import sqdtoolz as stz
 
 lab.load_instrument('src_sgs')
 stz.GENmwSource("MWcavity", lab, 'src_sgs', 'RFOUT')
+
 lab.HAL('MWcavity').Mode = 'Continuous'
 lab.HAL('MWcavity').Power = 14.5
 lab.HAL('MWcavity').Frequency = 8.1e9

docs/User/GENswitch.md

@@ -0,0 +1,20 @@
+# HAL `GENswitch` for Switches
+
+The `GENswitch` HAL manages switches typically used as follows:
+
+```python
+import sqdtoolz as stz
+#Initialise Laboratory object as lab
+...
+
+lab.load_instrument('sw_rpi')
+stz.GENswitch('sw_rpi', lab, 'sw_rpi')
+
+lab.HAL('sw_rpi').Position = "P1"
+```
+
+The `GENswitch` HAL simply sets the position of a given switch (whether it is over Ethernet or a serial COM port). The switch positions are typically given as `'P1'`, `'P2'` etc. for the given switch positions. Some special switches (like the [custom qubit control and readout box](CustomDevices/BoxIQmod.md)) may use other labels like `'Pmeas'` and `'Pmix'`. If unsure just use the `get_possible_contacts` function to query the possible switch states:
+
+```python
+lab.HAL('sw_rpi').get_possible_contacts()
+```

docs/User/InstrumentSpecific/Readme.md

@@ -13,6 +13,7 @@ FPGA DSP units:
 Microwave sources:
 - [Rohde & Schwarz SGS100A](RohdeAndSchwarz_SGS100A.md)
 - [Rohde & Schwarz SMB100A](RohdeAndSchwarz_SMB100A.md)
+- [Windfreak SynthHD PRO (v2)](WindFreak_SynthHD.md)
 
 Source-Measure-Units:
 - [Keithley 236](Keithley_236.md)