【95】The Birth of the Golden Coil: When All Said "Impossible"

【95】The Birth of the Golden Coil: When All Said "Impossible"

Last week, we received a special inquiry from a precision instrument manufacturer who needed an inductor coil that could operate at liquid helium temperature. The requirement was that the Q value should not decline by more than 5% at minus 269 degrees Celsius. After I quoted the price, the buyer was silent for three seconds, then their voice suddenly rose: "You're using gold wires? Are you crazy? The cost of gold wires is 47 times that of copper wires!" I didn't argue. Instead, I sent a video over - in the picture, our gold coil continued to work in liquid helium for 240 hours, and the test curve remained straight as before. Five minutes later, the phone rang: "We want to place an order, but we want to know why we must use gold."

In fact, six years ago when we first developed the coil for the superconducting quantum computer, we also asked the same question. At that time, the professor from the Chinese Academy of Sciences told us in the laboratory: "Copper wires will turn into 'insulators' at ultra-low temperatures, and silver wires will have lattice distortions. Only gold - its lattice structure remains stable under extreme conditions." But to actually make a coil with 99.99% pure gold with a diameter of 0.03 millimeters, everyone thought it was a fantasy. The most surprising thing was that when we found the largest gold wire supplier in China, the technical director of the supplier shook his head: "To make a coil with such fine gold wires? There is no mass production process in the world."

Why gold? Three physical facts are presented before us: First, gold is the only metal that still maintains excellent ductility at 4K ultra-low temperatures and won't break like copper; second, the skin effect of gold at GHz high frequencies is 30% lower than that of silver, reducing 87% of high-frequency loss; third, the diffusion rate of gold atoms is extremely low, and its performance degrades by no more than 0.1% after working for 100,000 hours in a vacuum environment. This is an ideal material solution written in textbooks but no one dared to implement. We spent 14 months and modified the drawing machine seven times, finally controlling the diameter of the gold wire to be 0.03 ± 0.002 millimeters - equivalent to half the thickness of a hair.

The most powerful proof comes from the quantum laboratory in Hefei. Their "Zu Chongzhi" quantum chip requires 128 sets of high-frequency inductors. Before using the gold-coated coils from European and American suppliers for testing, the Q value dropped to 63% of the initial value after continuous operation for 72 hours. After replacing with our pure gold coils, under the same test conditions, the Q value remained at 91%. The project's chief scientist noted in the acceptance report: "This is currently the only domestic coil that meets the requirements for 100,000 quantum operations with a fidelity rate." Now, among the six quantum computing projects under construction in China, five have specified our gold coil solution.

I remember the scene on the day the first batch of gold coils were shipped. Quality inspector Xiao Wu inspected the last coil under the microscope, and suddenly her eyes turned red. She whispered: "The gold ring left by my grandma was only 3 grams, and this batch of coils used 200 grams of gold." At that moment, I understood that we weren't showing off wealth, but were using the most precious material to overcome the most cutting-edge scientific challenges. When customers complained about the price, I would show them the operation data of the quantum computer - behind every stable entangled quantum bit, there is gold silently guarding in the ultra-low temperature environment.

This story began with a "crazy" material choice and ended with countless nights spent battling micro-millimeter gold wires in the clean room. As China's quantum computers continuously set new world records, those golden coils hidden in the vacuum chambers are emitting a more precious light than gold - it is the courage of China's precision manufacturing to challenge the limits. When customers complained about the price, I would show them the operation data of the quantum computer - behind every stable entangled quantum bit, there is gold silently guarding in the ultra-low temperature environment.

This story is about using the stability of gold to illuminate the future of quantum - Golden Eagle gold coil lays the foundation for cutting-edge technology.