Electronic PCB Boards Play in Quantum Computing
A simple analogy helps explain what makes electronic PCB boards so special. When you flip a coin, heads or tails are the possible outcomes, but there is some probability that it will land somewhere in between—a gray area. That’s how physicists describe the uncertainty involved in quantum computing.
A PCB is a foundation that supports and connects electrical components, from tiny ICs to advanced chips with high pin counts. These complex devices can have thousands of connections, so the copper connections on a PCB must be made precisely and reliably to ensure that all the parts work together in the correct order. electronic pcb board manufacturers fabricate insulating substrates from non-conductive materials like fiberglass-reinforced epoxy, and they etch circuit patterns into their surfaces to establish the connection points known as pads. The pads are what bind the copper wires to their respective component pins, and the resulting conductive pathways run across both sides of the board.
PCBs also provide the means to route these signals between components and to other systems, such as control or readout equipment. These signal-routing circuits are critical to achieving the full potential of a quantum computer because they convert the binary language of digital 1s and 0s into an analog signal that the qubits can “understand.” In addition, the control and readout signals must be transmitted without any interference from noise or magnetic fields.
What Role Do Electronic PCB Boards Play in Quantum Computing?
The signals are passed through a series of progressive temperature reduction stages in a facility called a dilution refrigerator (DR), which protects the system from vibrations and cosmic radiation. At each stage, the DR cools the components down to near absolute zero. The RF boards carry the analog signals to and from the qubits, through a number of circuit-level signal processing components including filters, amplifiers, attenuators, and switches. These circuits are all machined on hermetically sealed flanges and feed through a variety of high-quality connectors, bias tees, and cable assemblies — all of which must be non-magnetic to avoid interference with the physics of the qubits.
To transmit the microwave pulses that enable quantum computing, scientists use a radio frequency, or RF, board with more than 200 elements. These include mixers to adjust frequencies, filters to eliminate unwanted wavelengths, and amplifiers and attenuators to adjust the amplitude of the signals. In addition, the RF board has a commercial field-programmable gate array (FPGA) that acts as the brains of the quantum computer.
Despite these advances, the physics of quantum computers is still too new for major chipmakers to build integrated circuits (ICs) that can handle the complex readout and control functions. Until that day, the engineers at Fermilab must continue to build these specialized RF boards with custom components and coaxial interconnects. However, if the team can get these new RF boards up and running, it may be possible to scale up a quantum computer to solve real-world problems. That would be a mind-boggling achievement, and it would highlight the extraordinary capabilities that a quantum computer could offer in solving complex problems such as drug discovery, engineering design, and financial forecasting.
