In developing the OPX1000, a controller fit for the ever-growing quantum processors counting 1,000 qubits and beyond, we had to think deeply about every detail that impairs scalability. Our recently unveiled OPX1000 module for microwave generation (MW-FEM) generates pulses up to 10.5 GHz directly, without analog oscillators or mixers. The choice of technology to reach microwave frequencies is not trivial. We choose cutting-edge direct digital synthesis (DDS) for very specific reasons, and we believe it will enable scalability and performance to an even greater degree. In this blog, we dive deeper into the considerations for going this route and existing alternatives. So stick around, whether you like mixers or hate them, this will be an interesting ride.

Summary of Technologies for Microwave Operation
The control signals for qubit drive and readout often fall in the microwave range, which is outside the range of baseband controllers. Many qubit labs have solved the issue with solutions based on mixing, including single sideband mixers, IQ-mixers, or more complicated schemes such as double super-heterodyne (DSH) conversion. Mixer-based solutions make use of analog local oscillators (LOs) that are multiplied by the signal of a controller or an AWG. IQ-mixers naturally suffer from two main spurs (affectionate name for unwanted signals), the LO leakage and the mixer image, which require non-trivial calibration to be removed. Other schemes, such as double super-heterodyne, offer a zero-calibration solution but use many more components. Additionally, mixing schemes require having an LO source per mixer if different drive frequencies are used. Having a low phase source per mixer is very expensive, and in order to cut prices, will probably include a phase-lock loops (PLL), leading to phase differences between channels, which is detrimental for multi-qubit systems. In other words, while mixers can be useful, we need to be aware of the pros and cons involved.

In Sept. 2023, Quantum Machines (QM) unveiled OPX1000, our most advanced quantum control system to date - and the industry's leading controller in terms of performance and channel density. OPX1000 is the third generation of QM's processor-based quantum controllers. It enhances its predecessor, OPX+, by expanding analog performance and multiplying channel density to support the control of over 1,000 qubits. However, QM's vision for quantum controllers extends far beyond.

OPX1000 is designed as a platform for orchestrating the control of large-scale QPUs (quantum processing units). It's equipped with 8 frontend modules (FEMs) slots, representing the cutting-edge modular architecture for quantum control. The first low-frequency (LF) module was introduced in September 2023, and today, we're happy to introduce the Microwave (MW) FEM, which delivers additional value to our rapidly expanding customer base.

Quantum Machines, the provider of breakthrough quantum control solutions that accelerate the development of practical quantum computers, today launched its new advanced quantum control solution, OPX1000. Designed for quantum computers at scale, OPX1000 leads the industry across key performance metrics including feedback capabilities, runtime, analog performance and channel density. Building on the company's proven technology which is currently used in over 200 quantum computing facilities, OPX1000 is the ideal control solution for builders of the largest and most advanced quantum computers in the world. The solution is now being deployed with select customers at leading quantum research laboratories and will be generally available later this year.

Major technology companies like IBM and Microsoft have unveiled ambitious roadmaps to build quantum computers with over 100,000 qubits in the next decade. As the industry steadily progresses towards practical large-scale quantum computers, laboratories around the world will have systems with hundreds and even thousands of qubits within the next few years. Running a system at this scale requires a quantum control solution that provides stellar performance, while supporting advanced capabilities like automated setup, embedded calibration, real-time error correction and more.