The future of quantum technology doesn’t depend on every home, business, or organization owning a superpowered computer. Its true potential lies in the internet — in a network of connections that enables even lower-capacity machines to tap into the advantages of quantum computing, whether from research centers or corporations, ultimately benefiting end users.

But building such a network requires the ability to transmit quantum information between machines over long distances without relying on costly infrastructure. A study published in Nature on Wednesday marks a major step in that direction, demonstrating the coherent transmission of quantum data across 155 miles (250 kilometers) of standard fiber-optic cable in Germany — without the need for cryogenic cooling.

Mirko Pittaluga, lead author of the research and a scientist at Toshiba, calls the breakthrough a “record” — not just for the distance covered, but for the infrastructure used, and the coherence achieved in communication. “It is fundamental to the phase-based architecture of the quantum internet,” the researchers state in the paper.

Antia Lamas, director of the Quantum Networks Center at Amazon Web Services (AWS), who was not involved in the study, says this next-generation internet will be effective “when all the capabilities of the quantum network are available.” According to Lamas, its implications will be critical, “first in the area of security and, later, for connecting quantum computers and expanding their potential.” “These networks will allow us to implement amazing capabilities,” she told EL PAÍS.

The recent achievement goes beyond the 155-mile communication distance between Frankfurt and Kehl in Germany. The same research group previously demonstrated quantum data transmission over more than 372 miles (600 kilometers) of cable. What sets this study apart is the maintenance of quantum coherence using a conventional underground fiber-optic network under everyday environmental conditions.

This is significant because quantum communications have historically depended on specialized equipment — such as cryogenic systems — to reach the near-absolute-zero temperatures that particles need to preserve their properties.

Qubits, the basic unit of quantum information which are exponentially more powerful than conventional bits, are extremely fragile and prone to errors due to their interactions with the environment. The expansion and contraction of optical fibers caused by changes in environmental conditions — such as temperature fluctuations — introduce errors and cause them to lose coherence.

But the research published in Nature, in line with the previous work of the same team, has succeeded in overcoming this important limitation for the future quantum internet. “Our research aligns the requirements of coherence-based quantum communication with the capabilities of existing telecommunication infrastructure,” the researchers argue.

“With the new techniques we have developed, further communication distance extensions for QKD [Quantum Key Distribution] are still possible, and our solutions can also be applied to other quantum communication protocols and applications,” Pittaluga said after the 372-mile record.

Before this experiment, the researchers simulated conditions in the laboratory, but within a controlled temperature environment. However, these previous tests showed more fluctuations. Under real-world communication conditions, the team managed to preserve the system.

“In phase-based quantum communication systems, maintaining coherence among quantum states encoded by different users is crucial for system performance and error minimization,” explains the Nature study.

Carlos Sabín, a researcher in the Department of Theoretical Physics at the Autonomous University of Madrid (UAM), who was not involved in the study, welcomed the new study. “The most innovative aspect of these new results is that they use already-existing commercial optical fiber and do not add more sophisticated technology typically found in quantum physics laboratories, such as cavities or cryogenic refrigerators,” he told Science Media Center Spain.

“The quantum bits used are photons generated with lasers, in contrast, for example, to other previous experiments, such as the one published last year in Nature, in which quantum entanglement was generated in Boston between experimentally more complex systems, including the use of cavities. These systems might be more suitable for building quantum memories, but using optical photons, on the other hand, allows for quantum communication over very long distances.”

The physicist recalls another recent study, published in Optica, which tested quantum teleportation with photons over conventional, in-use optical fibers, although at a much shorter distance of about 18.6 miles (30 kilometers) and with error rates of 10%.

“These new results,” Sabín added, referring to Wednesday’s publication, “with small error rates of around 5%, represent a step forward in the possibility of creating quantum physics-based communication networks integrated with existing optical fiber technology in our cities. Although it should be noted that we are still at a very preliminary stage of development.”

Pittaluga’s team believes they have reached a fundamental milestone for the quantum internet: “Our work demonstrates the compatibility of coherence-based quantum communications with existing network infrastructure and the practical implementation of an effective quantum repeater over commercial networks. We also achieved, to our knowledge, the longest distances for real-world QKD using non-cryogenically cooled technology.”

“Our findings confirm that environmental conditions in operational telecommunications hubs are comparable to or even better than those simulated in laboratories, encouraging further commercialization and prototyping of coherent quantum communication equipment. This achievement lays the groundwork for future practical, high-performance quantum communications and networks,” he continued.

This high performance is another challenge in quantum communication. Traditional methods, such as quantum key distribution (QKD), with which Pittaluga’s team has worked, and others, like chaotic encryption, often sacrifice speed or transmission capacity for the sake of security.

However, in a study by researchers at Shanghai Jiao Tong University, they presented an integrated encryption and communication (IEAC) framework that combines robust security with high-capacity transmission performance, based on end-to-end deep learning (E2EDL), to achieve a record-breaking secure transmission of 1 TB per second over 745 miles (1,200 kilometers) of optical fiber, a milestone in communications over this secure, high-capacity, long-distance infrastructure.

“Our work bridges the gap between security and transmission performance in optical communications. By incorporating encryption at the physical layer, IEAC paves the way for secure, high-performance networks capable of supporting the data demands driven by AI,” says Lilin Yi, co-author of the study and a professor at Shanghai University.

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It all began in 2007. Jacqueline Stevens (1962) read about Pedro Guzmán, a mentally ill 31-year-old man who was jailed for a misdemeanor in Los Angeles, California, where he was born, when he was removed from the country as an illegal immigrant. Guzmán was deported to Mexico and spent three months adrift, sleeping on the streets and eating out of the garbage, while his family desperately searched for him. Learning of his story made the researcher and professor of political science at Northwestern University (Illinois) set out to study something that until then no one had analyzed in depth: how many U.S. citizens are deported by their own country’s immigration authorities, a phenomenon the federal government does not track on its own.

“It occurred to me that if this was happening to one person, it was probably happening to many others as well. That whatever the protocols were that led to Mr. Guzmán being deported were leading to other people who were citizens being deported as well,” Stevens tells EL PAÍS by telephone from Chicago.

She examined years of immigration court records, reviewed thousands of cases and government documents, and interviewed immigration judges, attorneys and deported citizens. And she found that at any given time, about 1% of those detained by immigration authorities and 0.5% of those deported are actually U.S. citizens. Although this is a small share of the total number of deportations that take place, the consequences can be traumatic, as they were for Guzmán.

Stevens’ work has become even more important now that Donald Trump’s administration is entertaining the idea of deporting U.S. citizens convicted of crimes. The president has said he is considering sending them to prisons in El Salvador, where he already transferred more than 200 immigrants without due process after accusing them of belonging to Latin American gangs. “The home-growns are next,” the Republican told Salvadoran President Nayib Bukele during his official visit to the White House last week.

His statement set off alarm bells of all kinds, but for Stevens, who founded the Deportation Research Clinic at Northwestern, it was nothing new.

Question. How alarming are the president’s latest comments about holding U.S. citizens in prisons in El Salvador?

Answer. I don’t see how this is even plausible. Leaving aside the constitutional issues, if you’re going to put somebody in federal custody as punishment, the facility has to conform with all sorts of regulations from the Federal Bureau of Prisons. To the extent that they’re able to implement any of those regulations outside the United States, it would be extremely expensive and really undermine the whole theater Trump has in mind, because those facilities would actually have to conform with the standards already in place in the U.S. And once that happens, it kind of takes the fun out of it for the president.

Q. And his argument is that it will actually be cheaper to do it in El Salvador.

A. Exactly, and it won’t be. There’s no loophole that says that you can have people in custody for federal crimes and not have the Bureau of Prison Regulations apply if you incarcerate them in El Salvador.

Q. But his administration is continuing to insist on it.

A. This is actually not new to Trump, but he’s trying to associate criminality with otherness and alienness, and therefore, taint the people who are in these kinds of proceedings and make the public think that it doesn’t matter if we put them in a different country. But to the extent that we are considering punishing people for stealing a car by sending them to El Salvador if they are citizens, we should also take a second look at our impulse to do that if they’re non-citizens as well.

Q. How do deportations of U.S. citizens take place? Since there should be legal protections to stop them from happening.

A. The problem is that there aren’t protections to stop this from happening. The premise of deportation proceedings is that the person that you have in custody is a non-citizen and therefore, the Constitution is able to provide very few protections to them. The issue with that is that when you make that assumption, you’re going to end up deporting the wrong people, including U.S. citizens. I want to be really clear about this: the reason I do this research is not because I care more about U.S. citizens than anybody else, but in fact to highlight exactly this problem. Because if you go into an immigration court as a U.S. citizen and still get deported, that tells us an awful lot about the low level of legal protections there for everybody else.

Q. This is going to sound really obvious, but can you explain why it’s illegal to deport U.S. citizens?

A. Immigration and deportation laws are only for non-citizens, they legally cannot apply to someone who is a U.S. citizen. It’s like asking, can you please explain why it’s illegal to find somebody who is innocent guilty? By definition, it’s impossible, and yet it happens.

Q. You started researching this because there wasn’t anyone else tracking this issue, least of all the government. Why do you think there’s so much secrecy around it?

A. There’s still no solid data on this in terms of the magnitude of how this is happening across the country. At some point, I thought I had a workaround to that. I thought that I would do a FOIA request for all the data indicating country of origin in cases in immigration court. Because I knew that some of these people were born in the United States, and in an immigration court proceeding, it should indicate that they were claiming that their country of origin was the United States. However, what I learned is that the Department of Justice Executive Office of Immigration Review, which is the agency that oversees the immigration courts, relies exclusively on the data of ICE [Immigration and Customs Enforcement] for that field. And ICE is never going to go into court and say, “Hey, here’s someone from the United States, judge, please deport them.” So their data indicated, in some cases, inaccurately, that the person was born outside the United States. That is pretty clear evidence that the federal government for decades has recognized that people in their custody were U.S. citizens.

Q. But they’re not going to publicly acknowledge it because then they would have to admit that they are doing something that is illegal.

A. And they don’t want to acknowledge that because they cannot run this system consistent with the U.S. Constitution and also admit that they’re deporting U.S. citizens. That’s actually been a huge problem in recent years. The more the research that I’ve done has gained traction in the media, the harder ICE is trying to push back in these cases of people claiming U.S. citizenship. In the past, they would pretty quickly acknowledge they made an error and release the person and terminate the deportation proceeding. But now they go to ridiculous extents to try to make those assertions.

Q. And that’s only going to get worse now under the Trump administration.

A. Exactly.

Q. In your research, have you noted any differences between people who were born in the U.S. and naturalized citizens when it comes to them being deported?

A. Ironically, it’s actually easier for people who are naturalized citizens to prove their citizenship than it is for people born in the United States or who have automatically acquired citizenship at birth. The reason for that is that if you’re naturalized, you have all the paperwork from Homeland Security that shows the process of your naturalization. If you’re born in the United States, it’s not that easy. Recently there was a case about a guy who was born in California. When he tried to return to the country with his birth certificate and so forth, the border patrol said, “oh, you must have gotten that fraudulently.”

Q. So even a U.S. birth certificate isn’t considered sufficient documentation anymore?

A. Even when you have the fingerprints and can prove that you’re the person who’s associated with the birth certificate, they still may not recognize that.

Q. Has anything struck you particularly in your research?

A. In a lot of these cases of U.S. citizens who are deported, ICE will spend a huge amount of time emphasizing their criminal record. And you can see that in the Guzmán case, where they talk about how this person was a gang member and so forth. As though to point that out is to justify deporting a U.S. citizen.

Q. It’s similar to what they’re now doing to Kilmar Abrego García in trying to justify his deportation even after admitting it was carried out in an administrative error. It’s all part of the same modus operandi.

A. And in that sense what Trump is saying is not new and in fact resonates with how ICE has been operating for quite some time.

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Charlotte Sweeney, a federal judge in Colorado, has joined the legal battle against the Donald Trump administration. From now on, the president must provide Venezuelan migrants with at least 21 days’ notice before any deportation — such as the controversial mid-March removals to El Salvador — during which time they can appeal in court.

This is the first time since the Republican took office that a court has imposed limits on how the new Trump administration must use the Alien Enemies Act of 1798, under which 238 migrants classified as “criminals” were deported to the Center for the Confinement of Terrorism (CECOT) in El Salvador.

Until now, the dozens of migrants expelled from the United States only learned they were being deported 24 hours beforehand. Over the past two months, family members have accused U.S. authorities of deception, saying many deportees believed they were headed to Caracas, only to be imprisoned in the dreaded Salvadoran mega-prison. Under this arrangement, President Nayib Bukele’s government receives around $20,000 per incarcerated migrant annually.

The decision by the Denver-based federal district judge follows a lawsuit from the American Civil Liberties Union (ACLU) — which currently represents deported immigrants and has sued the Trump administration over the expulsions to El Salvador. The lawsuit essentially demands that the migrants be afforded “due process.” That is, that individuals and their attorneys be notified of the potential deportation within 30 days, and for the government to be transparent when migrants are to be sent to a third country.

The ACLU told the Supreme Court that, “whatever due process may require in this context, it does not allow removing a person to a possible life sentence without trial, in a prison known for torture and other abuse, a mere 24 hours after providing an English-only notice form (not provided to any attorney) that gives no information about the person’s right to seek judicial review, much less the process or timeline for doing so.”

Judge Sweeney’s ruling, issued Tuesday, not only granted a temporary restraining order on the deportations but also required that future notices be provided in a “language the individual understands.”

Speaking to CBS News, Tim Macdonald, legal director of the ACLU of Colorado, thanked the court for putting “a stop to the Trump administration’s unlawful attempt to disappear Colorado residents to a Salvadoran mega-prison.”

He continued: “Due process is fundamental to the rule of law in this country, and the government has shown a rampant disregard for this essential civil right.”

Macdonald also argued that the Trump administration’s desire “to evade due process is a threat to all of us.”

The risk of violating due process

The erosion of due process has become a central concern since the Trump administration ramped up efforts to deport not only alleged members of the Tren de Aragua gang, but also in carrying out the largest mass deportation operations in U.S. history.

Juan Pappier, deputy director of the Americas Division at Human Rights Watch (HRW), told EL PAÍS that that his organization has documented several legal violations stemming from the March deportations.

Not only did the administration continue sending flights to the Central American country despite a judge’s order to stop them, individuals were deported in “error” — such as 29-year-old Salvadoran national Kilmar Abrego García, whose lawyers are demanding his return.

“When we shift the line of due process for migrants, we risk shifting it for everyone,” Pappier warns. “What affects Venezuelans and Salvadorans today could affect American citizens tomorrow as well.”

According to HRW, the administration is also violating rights by preventing detainees in El Salvador from contacting their families or lawyers, and because it is impossible for them to appeal to a judge. “What we are seeing is that the Trump administration wants to move forward with these deportations without giving them the opportunity to challenge them in court,” says Pappier.

But Trump himself hasn’t hidden his intention to prevent deportations from being decided by a judge. Earlier this week, he wrote on his Truth Social platform that it is impossible to prosecute all the people currently facing deportation.

“We cannot give everyone a trial, because to do so would take, without exaggeration, 200 years,” he posted. “We would need hundreds of thousands of trials for the hundreds of thousands of Illegals we are sending out of the Country.”

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