Siheyuan (traditional courtyard house): Starting with the Korean War, returning home to take charge

After He Nianhua left, He Yuzhu stood by the observation window of the ecological capsule, gazing absently at the wheat stalk that was sprouting ears. His son's words, "I want to grow vegetables on Mars," were still echoing in his mind. Mars, at its closest point to Earth, is 50 million kilometers away; radio signals would take nearly half an hour to travel back and forth, and any country could intercept them. He thought of quantum communication—the USTC project had been delayed for two years; they reportedly had a prototype, but it hadn't been delivered yet.

He picked up the phone and dialed Huang Shichang. "When will the prototype arrive?"

"It's already on its way, Dean He. But I must tell you in advance that this thing is a bit..."

"What's up?"

"It's a bit big."

Huang Shichang wasn't exaggerating. When this metal cabinet arrived at the Chengshan Research Institute, it took four workers to unload it from the truck using a trolley. The metal casing was painted with light gray anti-rust paint, and the front was covered with a dense array of indicator lights and knobs, while heat emanated from the ventilation holes on the sides. He Yuzhu squatted down and placed his palm on the ventilation hole, only to be burned and pull his hand back.

"How big?" he asked, standing up.

Huang Shichang pulled a crumpled instruction manual from his pocket, glanced at it, and then stuffed it back in. "1.8 meters high, 1.2 meters wide, 0.9 meters deep, and 340 kilograms. To be honest, I also think it's too heavy. But the vibration damping system of the optical platform is only this big; if it's smaller, the vibration won't be suppressed." He patted the metal cabinet, his voice dull, like patting a metal coffin.

Lin Jianguo stood to the side, his face pale. He squatted down to examine the wheels at the bottom, then stood up to measure the distance between the cabinet and the doorway. Turning to He Yuzhu, he said, "The Kunlun return capsule is 2.5 meters in diameter. It can hold three people, a week's worth of supplies, and experimental equipment. If we add this huge thing, the astronauts won't even have room to turn around. Dean He, this needs to be miniaturized for the spacecraft. At least compress it to the size of a suitcase, weighing less than 20 kilograms."

He Yuzhu didn't reply, but turned to look at Huang Shichang. "Director Huang, what do you think?"

Huang Shichang took off his glasses and wiped the lenses, a fine sheen of sweat appearing on his nose. "Director Lin is right. The prototype verifies physical feasibility, not engineering usability. We have now achieved quantum-encrypted transmission over a hundred kilometers with a bit error rate of 3.7% and an eavesdropping detection success rate of 99.6%. This is already considered a leading level worldwide. The Princeton group got stuck at fifty kilometers; our fiber optic coupling technology is far superior to theirs."

He Yuzhu walked to the side of the metal cabinet and opened the door. Inside, it was crammed with optical components and circuit boards; most prominently displayed was a quantum light source device wrapped in black blackout cloth. "How long will miniaturization take?"

Huang Shih-chang held up three fingers. "Three years. We redesigned the light source packaging, replaced the free-space optical path with fiber optic integration, and customized a dedicated readout circuit. The unit you see now uses more than 300 discrete optical components. With an integrated solution, we can reduce that to less than 20. The volume can be reduced to 0.1 cubic meters, and the weight can be controlled to around 20 kilograms."

"The maiden flight of the Kunlun is scheduled for 1985." He Yuzhu's voice was unhurried, but every word carried weight. "I can only give you two years at most. Before 1984, the miniaturized prototype must be delivered to the Chengshan Research Institute and its communication system with the Fifth Academy of Aerospace Science and Technology must be integrated. Every day later, the maiden flight of the Kunlun will be delayed by one day. Can you shoulder this responsibility?"

Huang Shichang froze. His hand hovered in mid-air, his lips twitching slightly. Lin Jianguo, standing beside him, stared at his profile. The entire laboratory was so quiet that the hum of the refrigeration compressor could be heard.

"Two years." Huang Shichang's voice was a little hoarse, but he nodded. "But you have to give me twelve people, transferred from the University of Science and Technology of China and Nanjing University of Posts and Telecommunications, four each in the fields of optics, electronics, and mechanics. In addition, the funding for miniaturization needs to be increased by 1.5 million."

He Yuzhu snatched the crumpled instruction manual from Huang Shichang's hand, took out a pen from his pocket, and wrote a line on the back: "Approved at 1.5 million, delivery within 24 months." He then signed his name and dated the document, and stuffed it back into Huang Shichang's hand.

"I'll coordinate the personnel. After you return to Nanjing, set up an independent laboratory. Don't mention the matter with the Chengshan Research Institute to anyone, including your superiors."

Huang Shichang folded the paper and put it in his pocket, his fingers still trembling slightly. He opened his mouth, as if to say something, but in the end he only said, "I understand."

He Yuzhu turned to Lin Jianguo and said, "Clean up the empty room next to the ecological cabin and use it as a laboratory for Director Huang. Test the quantum communication prototype in Chengshan first; it's safer than in Nanjing. Also, notify the Fifth Academy of Aerospace Science and Technology to send a chief engineer of the communication system to coordinate interface standards with Director Huang. Have a confidentiality agreement signed before he goes."

Lin Jianguo wrote it down in his notebook, closed it, glanced at the metal cabinet, and shook his head.

He Yuzhu saw Huang Shichang out of the laboratory. The motion-activated lights in the corridor turned on as they passed, then turned off one by one behind them. Huang Shichang walked slowly, glancing back at his precious prototype as he went, like a father leaving his son to spend the night at someone else's house.

"Dean He, I have a question." Huang Shichang stopped at the elevator entrance. "You just mentioned two years, and I know that's not a figure you came up with on a whim. There are people on the Kunlun spacecraft, and communication security is a matter of life and death. Quantum technology cannot be cloned, so any eavesdropping will be exposed. Once this system is on the spacecraft, every command from the astronauts, every set of telemetry data, will be unheard by anyone, whether it's the KGB or the CIA. You're in such a hurry because you value this."

The elevator doors opened. He Yuzhu stepped inside, followed by Huang Shichang. The elevator slowly ascended, the floor number jumping from -3 to -2.

"You're right," He Yuzhu said, staring at the fluctuating numbers, "but there's one thing you're wrong about."

"What is it?"

"Quantum communication is not just for spacecraft. In the future, every diplomatic telegram, every financial transaction, and every military command from China can be encrypted using quantum encryption. The Americans use mathematical algorithms to protect their secrets; we use the laws of physics to protect ours. Mathematics can be cracked, but physics cannot."

The elevator doors opened on the first floor. Sunlight streamed in through the glass doors of the lobby, casting a bright white glow on the terrazzo floor. He Yuzhu walked to the main entrance, Huang Shichang following behind, and hailed a taxi.

Before the car door closed, Huang Shichang poked his head out. "Dean He, I've heard you're working on warp drive. Is it related to space?"

He Yuzhu bent down and leaned closer to the car window, lowering his voice. "Director Huang, can you produce the blueprints for your fiber optic integration solution in three months?"

Huang Shichang was taken aback, knowing he wouldn't get any results, and sighed. "Yes."

"Then let's draw up the blueprints first. I'll tell you some things after the blueprints are finished."