Quantum computing system having flex circuit boards for improved signal transmissions

A quantum computing system, comprising:

• one or more classical processors;
• quantum hardware comprising one or more qubits;
• a chamber mount configured to support the quantum hardware;
• a vacuum chamber configured to receive the chamber mount and dispose the quantum hardware in a vacuum, the vacuum chamber forming a cooling gradient from an end of the vacuum chamber to the quantum hardware;
• at least one first flex circuit board coupled to the one or more classical processors by a classical-flex interconnect, the at least one first flex circuit board comprising copper;
• at least one second flex circuit board coupled to the at least one first flex circuit board by a first flex-flex interconnect, the at least one second flex circuit board comprising a copper alloy;
• at least one surface mount attenuator board comprising one or more surface mount attenuators coupled to the at least one second flex circuit board, the at least one surface mount attenuator board comprising copper;
• at least one third flex circuit board coupled to the at least one surface mount attenuator board by a second flex-flex interconnect, the at least one third flex circuit board comprising niobium;
• at least one fourth flex circuit board coupled to the at least one third flex circuit board by a third flex-flex interconnect, the at least one fourth flex circuit board comprising copper;
• and
• a connector configured to couple the at least one fourth flex circuit board to the quantum hardware.

A quantum computing system, comprising:

• one or more classical processors;
• quantum hardware comprising one or more qubits;
• a chamber mount configured to support the quantum hardware;
• a vacuum chamber configured to receive the chamber mount and dispose the quantum hardware in a vacuum, the vacuum chamber forming a cooling gradient from an end of the vacuum chamber to the quantum hardware;
• a plurality of flex circuit boards comprising one or more signal lines, each of the plurality of flex circuit boards configured to transmit signals by the one or more signal lines through the vacuum chamber to couple the one or more classical processors to the quantum hardware;
• two or more surface mount attenuators coupled to the one or more signal lines;
• and
• an isolation plate configured to block cross-talk between the two or more surface mount attenuators.