Researchers at Lawrence Berkeley National Laboratory are pushing the boundaries of quantum computing by focusing on the complete system needed to harness its potential, not just the qubits themselves. Central to this effort is maintaining a superconducting quantum processing unit at 20 millikelvin, a temperature colder than outer space and just 0.02 degrees above absolute zero, using specialized dilution refrigerators that resemble “golden chandeliers with cables running up and down.” These cables are critical for both sending control signals to the processor and receiving information from it at room temperature. “Making a functional quantum computer requires much more than qubits alone; it takes an entire technology stack that can harness quantum science for real-world applications,” explains Chris Spitzer, operations lead at the Advanced Quantum Testbed (AQT). This holistic approach, encompassing hardware, software, and controls, is essential for achieving error-corrected quantum calculations and unlocking breakthroughs in fields from drug development to cosmology. Superconducting QPU & Dilution Refrigerator Operation Maintaining a stable quantum environment demands temperatures far beyond those experienced in natural settings; the superconducting quantum processing unit (QPU) at the heart of these systems operates at a frigid 20 millikelvin. This temperature, a mere 0.02 degrees above absolute zero, is even colder than the vacuum of outer space and is essential for preserving the delicate quantum information encoded within the qubits. The system delivers the control microwaves necessary to manipulate the qubits and, equally importantly, transmits the resulting quantum information back to room-temperature electronics for analysis. This “stack” isn’t simply an assembly of components, but a carefully integrated system where each element’s performance impacts the others. A key challenge lies in scalability; current wiring configurations, with one or more wires per qubit, become impractical as QPU sizes increase beyond a few hundred qubits. Researchers are actively investigating new low-noise wiring technologies