Synchronization#
In this section, we explain how to synchronize multiple instruments in your setup including Qblox instruments. Synchronization is based on two aspects:
1. A shared reference clock, preferably phase aligned, so that all instruments use the same reference to base their operations on.
2. A synchronized start event, so that all instruments start their operations simultaneously.
The following subsections will go into more detail on how to achieve both aspects. This page considers the external connections on the Cluster Management Module and the connections inside the mainframe. For convenience, the image of the CMM front panel as well as the block diagram of the Cluster backplane are shown below.
Reference clock#
Like most instruments, the Qblox instruments use a 10 MHz clock as a time reference.
To synchronize multiple instruments in your setup you will need to connect such a reference clock to
the REFin SMA connector of all the cluster CMM module (10 MHz, 1 Vpp nominal @ 50 Ω)
(see section CMM module) and set the reference_source() parameter to external.
Connecting the reference can be done through an external reference clock that is distributed with a star configuration to all instruments.
Here the output from the external clock needs to be split by the number of clusters with cables of equal length and connected to the REFin SMA connector of the cluster.
Note
Daisy-chaining the reference clock from one QBlox CMM module to the next is not supported. This does not yield a synchronised system with any reasonable or specififed cable length.
SYNQ#
To synchronize the start event of the instruments, Qblox SYNQ technology can be
used to greatly simplify the process. All modules within a cluster share the same
SYNQ network. Clusters can also be daisy-chained to each other to share the same
SYNQ network using the SYNQ cable.. Additionally, the Sequencer.sync_en() parameter needs to be set
for every sequencer in the instrument participating in the
experiment and these same sequencers need to execute the wait_sync instruction
(see section Instructions). Note that these last
two steps also need to be executed when only using
a single Qblox instrument. The Qblox SYNQ technology will then automatically
align the timing of every participating sequencer in all Qblox instruments to
within 300 ps of one another.
Trigger#
If desired, the Qblox instruments can also be triggered by other instruments using an external trigger signal. To achieve this, simply connect the external trigger signal to the TRIGin SMA connector (0-3.3 V, high-Z). Then follow the instructions in the External trigger input section to configure the external trigger input. Any sequencer in the Qblox instrument can then synchronize to the experiment by executing the wait_trigger instruction (see section Instructions).
Markers#
Additionally, the marker output channels can be controlled by the sequencers using the set_mrk instruction to trigger other instruments, thereby synchronizing them with the Qblox instruments (see section Instructions). However, care needs to be taken to compensate for any trigger delay caused by the connection or the triggered instrument itself.