Nadia sat on a stool behind Priya’s chair with her own laptop open on her knees and watched the numbers come off it. The atoms sat in their grid a few millimeters across. For four hours Priya had been running a calibration that would have taken Nadia’s lab a year. Every so often she let Nadia look at the magnetometer channel, which was a side effect of the calibration that Priya didn’t care about, but that mattered to Nadia.
Nadia was looking for three hertz.
It had been gone since Friday. Her own probe in the basement could not find it any more, and she had walked the room with the fluxgate every morning since. Priya’s atoms were better at noticing magnetic fields than anything Nadia was ever going to build. If the wobble was still in the building, it would show up here.
It didn’t. The channel was flat.
“You’re frowning at my baseline,” Priya said without turning around.
“It’s a good baseline.”
“I know it’s a good baseline. That’s why I don’t like you frowning at it.”
The students called the array Gertrude. Nobody remembered why. There was a strip of masking tape on the vacuum housing with GERTRUDE written on it in a green Sharpie, and under that, in different handwriting, do not feed after midnight.
Kayla came in at eleven with her laptop open in both hands like a tray.
“Sorry,” she said. “You need to see this.”
Priya held up one finger and finished what she was doing. Then she turned around.
On the laptop was a news site. Three exchanges had stopped trading. They also weren’t letting anyone withdraw cash. Coins that had not moved in fifteen years had moved overnight. A developer was quoted saying the network could no longer tell an owner from a thief. Under the headline were two photographs: a man laughing at a conference, and a girl at seventeen.
Nadia stared at the photographs.
Seth had called her at 7:04 on Tuesday morning, before the market opened, before anyone was on television, and asked her in his careful voice whether the quantum world was boring. Then he had asked her to keep his name out of it. He had known. He had let her make his phone calls for him.
She had told him on Saturday that she was done. She was angrier now than she had been on Saturday.
“Nobody’s array does that,” Kayla said. “Right? That’s like a million qubits.”
“More,” Priya said.
“So how?”
Priya looked at Nadia.
“Somebody’s method is a lot better than anybody’s machine,” Nadia said. “That’s the only way it works.”
“How much better?”
“I don’t know. Better than anything I’ve read.”
“Then I hope they’re nice people,” Priya said, and turned back to Gertrude. “Kayla, close that. I have forty minutes left and I’m not spending them on Bitcoin shit.”
Kayla closed it. Nadia did not say anything about a man in a gray fleece, or about the names she had given him, one of which was Priya’s.
At twelve-thirty Priya shut the calibration down and stretched until her back cracked.
“I didn’t get your three hertz for you.”
“It’s gone. It’s been gone since Friday.”
“Then it was a truck.” Priya was already packing up. “Or a person.”
Nadia thought about the man in the gray fleece standing next to the seminar board with his hands in his pockets. That was stupid. People did not make three hertz.
“You want Thursday night?” Priya said. “I have six hours I’m not going to use. My kid has a tournament.”
Nadia almost told her then. Priya was zipping her bag and not looking at her, and it would have taken one sentence.
“Yes,” Nadia said.
“Bring your own snacks. The last person ate my granola.”
Nadia went back down to the basement.
The lab was cold and quiet and smelled like the cleaning solution the custodians used on the stairs. She sat down at her desk and took Lund’s card out of the drawer where she had put it on Friday, and laid it on the desk in front of her next to her phone.
She could call Seth. She had told him not to call her, but she could call him and tell him exactly what she thought of someone who used his friends as an early warning system. She would enjoy about ninety seconds of it. Then he would apologize, say something reasonable, and she would end up doing him another favor.
She could call Priya. She had spent four hours sitting two feet behind her, and there had been at least twenty times in those four hours to say it.
Or she could call the people whose job it was to deal with stuff like this.
Nadia had never called the FBI in her life. She looked up the Denver field office number, called, and got a recording, then a menu, then a woman who asked her what it was regarding, then a man who said his name too fast to catch and that he was a special agent.
“I want to report something,” Nadia said. “A man came to my lab at the university on Friday and asked me about phone calls I made on Tuesday. About the Bitcoin transaction. He had a card from a company called Ardmore Risk Advisory. He said his name was Peter Lund.”
“Can you spell Ardmore for me?”
She spelled it. He asked her to spell Lund. She spelled that too.
“And what did he ask you, exactly?”
“He asked who I called on Tuesday about it.”
“Who did you call on Tuesday?”
“I’m not calling to tell you that.”
“Ma’am, it would help us to understand —”
“I’m calling to tell you there’s a man going around the university asking people who they called. He knew the answers before he asked. He didn’t ask me anything about the physics. If he works for an exchange, fine, then you can tell him to stop. If he doesn’t, then you should want to know who he does work for.”
She heard him typing.
“Can I get your name and a number?”
She gave him both. He read them back correctly.
“Someone will follow up with you,” he said.
“When?”
“I can’t tell you that. We’re getting a very high volume right now.”
“I bet.”
“Is there anything else you want to tell me about this, ma’am?”
There was. Seth, at 7:04 on Tuesday, asking if the quantum world was boring.
“No,” Nadia said.
She hung up and sat looking at the card. Then she put it back in the drawer, because it might be evidence now, and she didn’t know what you were supposed to do with evidence.
She felt worse than she had before she called. She got up and picked up the fluxgate on its dowel and walked the room one more time, the whole perimeter, and then the northeast corner under the conduit at three different heights.
The number did not move.