In/Out Tab¶
The In / Out tab provides access to the settings of the Instrument’s Signal Input and Signal Output of the Quantum Analyzer Channel, as well as the Instrument’s Signal Outputs of the Signal Generator Channels. It is available on all SHFQC+ Instruments.
Features Overview¶
- Enable/disable inputs and outputs
- Define the Center Frequency of the modulation and analysis bands
- Define the input and output power ranges
- Switch between Radio Frequency (RF) and Low Frequency (LF) paths on the Signal Generator Channels
Description¶
Control/Tool | Option/Range | Description |
---|---|---|
Output | Quick overview and access to all the settings for configuring the analog upconversion path. |
The SHFQC+ uses the double super-heterodyne frequency upconversion technique to generate its RF output frequencies. The SHFQC+ has two types of channels: One Quantum Analyzer Channel for performing qubit readout measurements, and 2, 4, or 6 Signal Generator Channels for generating signals to control the qubit states.
Note
It is highly recommended to enable all required inputs and outputs and wait for 2 hours after powering on the instrument.
Note
Please wait for at least 0.5 seconds after switching the center frequency or power range before running a measurement.
Note
Please do not change the center frequency or input range while acquiring data. Mishandling of this could lead to an invalid scaling of the result vector.
Signal Generator Channels¶
Each Signal Generator Channel has its own frequency upconversion chain. Each Signal Generator Channel has two available Output paths: the RF path for generating signals with center frequencies from 0.6 GHz to 8 GHz, and the LF path for generating signals with center frequencies from 0 GHz to 2 GHz. When using the RF path, center frequencies determine the frequency of an analog synthesizer and can be set with a resolution of 0.2 GHz. All variants of the SHFQC+ contain 4 synthesizers. The Quantum Analyzer Channel uses one synthesizer, and each pair of Signal Generator Channels share one synthesizer. This means that Signal Generator Channels 1 and 2 must share the same RF center frequency when using the RF path. To achieve different output frequencies on Signal Generator Channels 1 and 2, digital modulation must be employed (see the Modulation Tab). When using the LF path, the center frequencies of each channel must be a multiple of 0.1 GHz can be set independently of the other channels in all variants of the SHFQC+ Instrument.
Note
The LF and RF paths can be programmed with the same sequences (see the
tutorial Basic Waveform Playback) but
the LF path has a smaller latency than the RF path due to the
differences in the analog part of the signal path. The differences in
latencies can be compensated by appropriate use of the playZero
command, described in the Tutorials.
When using the Signal Output of the RF path, the digital 1-GHz-wide modulation band centered around DC is first interpolated by a factor of 3, then digitally upconverted to 2 GHz (light blue elements) before it is passed to the 14-bit DAC. The resulting 2 GHz analog signal (dark blue elements) is then converted to 12 GHz by means of a local oscillator at 10 GHz. To remove all unwanted spurious signals, the signal is strongly filtered before it is down-converted in a second mixing process with a variable local oscillator. Depending on its software-controllable frequency value, the final output frequency band has a center frequency between 0.6-8 GHz and a width of ±0.5 GHz. Several amplifiers, attenuators, and filters in the up-conversion chain ensure that the different elements are not saturated and that the DAC range is faithfully mapped to the selected Output Range.
When using the LF path, the digital 1-GHz-wide modulation signal is still interpolated by a factor of 3 and passed to the 14-bit DAC, but the analog upconversion chain is bypassed. The center frequency is determined by setting the frequency of the oscillator used in the digital upconversion (fixed at 2 GHz when using the RF path, and can be set to a multiple of 100 MHz in the range 0 - 2 GHz when using the LF path). In this way, signals with center frequencies between 0 and 2 GHz can be generated with the LF path.
The advantages of this up-conversion scheme compared to IQ-mixer-based frequency conversion are that it is calibration-free, wide-band, and stable, in addition to having superior spurious tone performance. The optimal selection of the different gains, attenuators, and filters in the frequency conversion chains are taken over by the SHFQC+, such that only a few settings need to be set in the Output band parameters of the SHFQC+: Center Frequency, Output Range, and Output On.
Note
For both the LF and RF paths, the output power can be set in steps of 5 dBm, in the range -30 dBm to +10 dBm for the RF path and -30 dBm to +5 dBm for the LF path. If the power is set to a value that is outside this range or not a multiple of 5 dBm, the value will automatically be rounded to the nearest multiple of 5 dBm within the range for the path.
Quantum Analyzer Channel¶
The Quantum Analyzer Channel of the SHFQC+ uses a similar up-conversion chain as for the Signal Generator Channel. For the Signal Output, the digital 1-GHz-wide analysis band centered around DC is first interpolated by a factor of 3, then digitally up-converted to 2 GHz (light blue elements) before it is passed to the 14-bit DAC. Then, the analog signal (dark blue elements) is mixed to 12 GHz by means of a local oscillator at 10 GHz. To remove all unwanted spurious signals, the signal is strongly filtered before it is down-converted in a second mixing process with a variable local oscillator. Depending on its software-controllable frequency value, the final output frequency band has a center frequency between 1-8 GHz and a width of ±0.5 GHz. Several amplifiers, attenuators and filters in the up-conversion chain ensure that the different elements are not saturated and that the ADC range is faithfully mapped to the selected Output Range.
The Signal Input down-conversion chain (dark blue elements) works analogously, but in the backwards direction. The main differences to the Signal Output are the missing selectable filter and the conversion to 3 GHz instead of 2 GHz before the digitization through the 14-bit ADC. Because of the sampling rate of 2 GSa/s, the 3 GHz signal appears as a 1-GHz signal in the digital domain (light blue elements) before being down-converted to DC.
Similar to the SG Channels, the QA channel has both an LF and RF path. On the QA Channel, the frequency range of the LF path is from DC - 800 MHz. The LF path can be enabled for the QA Input, for the QA Output, or for both. If the LF path is enabled for both QA Input and QA Output, the frequency of the oscillator before the DAC is set to 0 Hz, then the signal after the DAC is sent out through the output "LF Path", and the input signal through the input "LF path" is converted by the ADC and then mixes with the oscillator at 0 Hz before integration.
Frequency Representation¶
The frequency \(f_{\mathrm{out}}\) of the output signal on each channel can be calculated as
where \(f_0\) is the center frequency (Center Freq (Hz)), \(f_{\mathrm{offset}}\) is the offset frequency (Offset Freq (Hz)) set by either a Digital Oscillator, or an uploaded waveform (see in Quantum Analyzer Setup Tab or Digital Modulation Tab). The range of \(f_{\mathrm{offset}}\) is from -1 GHz to 1 GHz. Please note that signals with an absolute offset frequency greater than 500 MHz will be attenuated significantly.
The frequency \(f_{\mathrm{in}}\) of the input signal on each channel can be calculated as
where \(f_{\mathrm{IF}}\) is the intermediate frequency (IF) after frequency down-conversion. The down-converted signal can be monitored by the SHFQC+ Scope. In resonator spectroscopy experiments, the signal with \(f_{\mathrm{IF}}\) is integrated by the same Digital Oscillator. In qubit readout experiments, it is integrated by an uploaded waveform.
Power Representation¶
The power \(P_{\mathrm{out}}\) of the output signal on each channel is calculated as
where \(P_{\mathrm{range,\ out}}\) is the output power range in units of dBm, \(g_{\mathrm{osc}}\) (\(g_{\mathrm{osc}} \le 1\)) is the amplitude gain of the Digital Oscillator, \(A\) (\(k\le1\)) is the amplitude of an uploaded waveform. Please note that the 14-bit vertical resolution of the output signal counts both waveform amplitude and oscillator amplitude gain in Spectroscopy mode. To have full 14-bit vertical resolution on the uploaded waveform, the amplitude gain of the oscillator has to be 1.
The input signal can be monitored by the SHFQC+ Scope. The power \(P_{\mathrm{in}}\) of the input signal on each channel can be calculated as
where \(A_{\mathrm{IF,\ I}}\) (\(A_{\mathrm{IF,\ Q}}\)) is the amplitude of IF I (Q) components displayed on the SHFQC+ Scope in units of RMS voltage (V) in the RF (LF) path. The \(P_{\mathrm{in}}\) is calculated in units of dBm.
In / Out Tab in the LabOne GUI¶
The In / Out settings can be accessed through the In / Out tab of the LabOne general user interface for the SHFQC+. After clicking on the tab, an overview subtab opens that displays all settings for all available Quantum Analyzer and Signal Generator Channels.
With the selectors at the left side of the In / Out tab, the detailed view of the up-conversion chain for the different Signal Generator Channels can be displayed, as well as the down-conversion chain for the Quantum Analyzer Channel. Each detailed view shows the available settings in the first, leftmost panel. In the second panel, graphical representations of the currently selected parameters of the up-conversion chain and down-conversion chain (if applicable) are displayed.
Functional Elements¶
The following Table 2 summarizes all settings. The modes are all accessible through the SHFQC+ nodes in Device Node Tree.
Control/Tool | Option/Range | Description |
---|---|---|
QA Channel | ||
Input On | On/Off | Enables the Signal Input. |
Input Range | RF: -50 dBm to +10 dBm LF: -30 dBm to +10 dBm |
Sets the maximal input power range that maps to the full scale of the ADC. The Ranges decrease in steps of 5 dB from +10 dBm. |
Input Overload Status | grey/yellow/red | Indicates whether input power on the front panel \(P_{\mathrm{in}}\) is or was above input power range \(P_{\mathrm{in, \ range}}\) . red: \(P_{\mathrm{in}}\) is > \(P_{\mathrm{in, \ range}}\) yellow: \(P_{\mathrm{in}}\) was > \(P_{\mathrm{in, \ range}}\) within the last 200 ms grey: \(P_{\mathrm{in}}\) is ≤ \(P_{\mathrm{in, \ range}}\) Note that Input Overload condition may damage the Instrument. Please avoid it by increasing Input Range or attenuating input signal. |
Input Path | RF or LF path | Select RF (0.5 - 8.5 GHz) or LF (DC - 800 MHz) input path. |
Center Frequency | RF: 1-8 GHz LF: 0 Hz |
Sets the center frequency of the analysis band in Hz. The frequency is rounded to the nearest multiple of 200 MHz. It is common to both the Input and Output of the same readout channel. |
Output On | On/Off | Enables the Signal Output. |
Output Range | RF: -30 dBm to +10 dBm LF: -30 dBm to +5 dBm |
Sets the maximal output power range that maps from the full scale of the DAC. The Ranges decrease in steps of 5 dB from +10 dBm (RF) or +5 dBm (LF). |
Output Overload Status | grey/yellow/red | Indicates whether output amplitude scaling factor \(g_{\mathrm{DAC}}\) before DAC is or was above 1. It is checked for an overload condition every 10 ms. red: \(g_{\mathrm{DAC}}\) is > 1 yellow: \(g_{\mathrm{DAC}}\) was > 1 within the last 200 ms grey: \(g_{\mathrm{DAC}}\) is ≤ 1 Note that overshot of square pulse could cause Output Overload, and using e.g. flat-top Gaussian could avoid this. |
Output Filter | Center frequency in RF path: Filter frequency 0.6 - 1.2 GHz: 0.1 - 1.5 GHz 1.4 - 3.0 GHz: 0.1 - 3.5 GHz 3.2 - 5.4 GHz: 2.5 - 6.0 GHz 5.6 - 8.0 GHz: 5.0 - 10.0 GHz |
Indicates selected filter in the RF path. The filter value is selected according to the center frequency value and ensures that higher signal harmonics are removed at the Signal Output |
Output Path | RF or LF path | Select RF (0.5 - 8.5 GHz) or LF (DC - 800 MHz) output path. |
Center Frequency | RF: 1 - 8 GHz LF: 0 Hz |
Sets the center frequency of the analysis band in Hz. The frequency is rounded to the nearest multiple of 200 MHz. It is common to both the Input and Output of the same readout channel. |
RF/LF Interlock | On/Off | Enables the RF/LF path interlock between input and output. If enabled (1), the output path is always configured according to the input. The default value is disabled (0). |
SG Channels | ||
Center Frequency | RF: 0.6 - 8 GHz LF: 0 - 2 GHz |
Sets the center frequency of the analysis band in Hz. The frequency is rounded to the nearest multiple of 200 MHz (100 MHz) when using the RF (LF) path. |
Output On | On/Off | Enables the Signal Output. |
Output Range | RF: -30 dBm to +10 dBm LF: -30 dBm to +5 dBm |
Sets the maximal output power range that maps from the full scale of the DAC. The Ranges decrease in steps of 5 dB from +10 dBm (RF) or +5 dBm (LF). |
Output Overload Status | grey/yellow/red | Indicates whether output amplitude scaling factor \(g_{\mathrm{DAC}}\) before DAC is or was above 1. It is checked for an overload condition every 10 ms. red: \(g_{\mathrm{DAC}}\) is > 1 yellow: \(g_{\mathrm{DAC}}\) was > 1 within the last 200 ms grey: \(g_{\mathrm{DAC}}\) is ≤ 1 Note that overshot of square pulse could cause Output Overload, and using e.g. flat-top Gaussian could avoid this. |
Output Filter | Center frequency in RF path: Filter frequency 0.6 - 1.2 GHz: 0.1 - 1.5 GHz 1.4 - 3.0 GHz: 0.1 - 3.5 GHz 3.2 - 5.4 GHz: 2.5 - 6.0 GHz 5.6 - 8.0 GHz: 5.0 - 10.0 GHz |
Indicates selected filter in the RF path. The filter value is selected according to the center frequency value and ensures that higher signal harmonics are removed at the Signal Output |
Output Path | RF or LF path | Select RF (0.1 - 8.5 GHz) or LF (DC - 2 GHz) output path. |
Digital Mixer of SG Channels | ||
Reset Channel | All or any available channel | Reset only the selected channel. |
Reset Mode | Manual/Automaic | Configure the NCO (before DAC) reset mode. In Manual mode the instrument does not automatically reset NCOs when switching a channel from LF to RF mode. In Automatic mode the instrument automatically resets the NCOs of all channels whenever a channel is switched from LF to RF, in order to restore alignment. |