Quantum Sensing Will Test Legal Frameworks for Privacy

Emerging quantum technologies are reshaping computation, communication, and sensing, requiring legal scholars to confront the consequences these developments will have for privacy law. As one of us has previously argued, quantum technologies can both enhance and erode privacy. While much of the debate has focused on quantum computing and its implications for data and informational privacy, emerging research on quantum sensing compels a closer examination of this evolving field and its privacy implications.

Quantum sensing exploits quantum mechanical phenomena to achieve sensitivities far beyond those of classical devices. These technologies leverage interactions at atomic and subatomic levels to detect incredibly small changes in physical parameters. One of the most familiar quantum sensing-based technologies today is the Global Positioning System, or GPS, which became operational in 1990.

Quantum sensing technologies have moved well beyond theoretical speculation; they are advancing rapidly, with prototypes already demonstrating capabilities once thought unattainable. This essay examines several of these emerging technologies, the profound challenges they pose to established conceptions of privacy, and the urgency of integrating quantum sensing into broader conversations on technological governance.

Privacy is not merely a policy preference; it is a fundamental right. In the United States, it dwells in the “penumbras” of the Bill of Rights; the Fourth Amendment protects against “unreasonable” searches. Internationally, Article 17 of the International Covenant on Civil and Political Rights prohibits “arbitrary” interference with privacy. Both frameworks require that intrusions be proportionate to legitimate aims.

Quantum sensing technologies will test these frameworks severely because they bypass the physical boundaries—walls, distance, the opacity of the human body—on which existing privacy doctrine depends. The privacy-eroding aspects of quantum sensing can be grouped into four categories: government surveillance, corporate monitoring, personal intrusion, and security vulnerabilities. Different quantum sensing technologies can fall into one or several of these categories. By considering the primary and secondary privacy impacts of each category, scholars, lawmakers, and ordinary citizens can better assess which uses demand regulation, prohibition, or incentivization.

Framing quantum sensing within a structured privacy impact model will be an important step toward fostering thoughtful and creative legal analysis in this emerging field—and toward avoiding the recurring pattern of past technological revolutions, where law lagged perilously behind innovation. While emerging privacy threats are not entirely new, quantum sensing amplifies and accelerates them, exposing the inadequacy of existing privacy frameworks in addressing faster, more pervasive forms of intrusion. The discussion that follows explores four such technologies in detail.

Emerging quantum sensing technologies

Several types of quantum sensors are under active development, each posing distinct privacy challenges: quantum magnetometers, quantum gravity sensors, quantum LiDAR and quantum radar, and quantum RF sensors and receivers.

Quantum magnetometers

Quantum magnetometers are highly sensitive instruments that measure magnetic fields, detecting signals too weak for conventional sensors. They can locate sources of radio waves, such as hidden transmitters, with far greater accuracy than traditional passive devices. Notably, they may even be able to detect the faint magnetic fields generated by the human heart or brain. Although practical deployment remains an open question, as with many emerging technologies, these devices illustrate how quantum sensing could enable previously inconceivable forms of biological or electronic surveillance, while also diminishing geolocation privacy by disclosing someone’s presence.

Quantum gravity sensors

Quantum gravimeters detect tiny variations in the Earth’s gravitational field. Because every object slightly distorts this field, these sensors can reveal hidden features such as underground tunnels or buried pipelines. Unlike GPS, which cannot transmit signals underground or underwater, quantum gravimeters can operate in these otherwise inaccessible environments. These sensors raise novel concerns about the capacity to observe private spaces without any physical intrusion, challenging foundational assumptions about spatial privacy and legal protections tied to physical boundaries—a concern that has already been the subject of several cases reaching the US Supreme Court. At the same time, such technology can also enhance privacy by enabling the detection of intrusions or unauthorized surveillance, illustrating its dual-use nature. Whether a given technology enhances or diminishes privacy depends not on its inherent characteristics, but on how it is deployed.

Quantum LiDAR and quantum radar

Quantum LiDAR, a light detection and ranging technology, is an advanced imaging system capable of identifying objects with exceptional sensitivity, even at extremely low signal levels and in high-interference environments. In conventional systems, such interference may arise from atmospheric conditions such as rain, fog, snow, or smoke, or from competing electromagnetic signals, all of which can degrade detection accuracy. Quantum LiDAR, by contrast, can generate highly precise three-dimensional images that penetrate fog, obscure disguises, or even “see” around obstacles. While these capabilities offer clear advantages for navigation and safety, they also raise privacy and surveillance concerns, as they could enable the identification of individuals or activities otherwise hidden from view—tracking a person’s movements inside a building, for instance, or monitoring gatherings behind walls or in enclosed spaces.

Quantum RF sensors and receivers

Quantum-enhanced radiofrequency (RF) sensors can detect electromagnetic signals with exceptional sensitivity over a broad range of frequencies. A single quantum RF sensor can monitor a wide spectrum and detect signals far too faint for conventional systems to capture. This capability could enable not only the interception of extremely weak radio communications but also the detection of passive electromagnetic leaks from electronic devices. Such leaks are unintended emissions—low-level signals produced by components like processors or memory modules as a byproduct of normal operations. Even when devices such as computers or smartphones are not actively transmitting, these emissions can be intercepted and analyzed to reveal sensitive information: what is typed on a keyboard, for instance, or what appears on a screen. As scholars have noted, this is especially significant for privacy as it relates to Internet of Things (IoT) devices and wearable artificial intelligence technologies, given their widespread deployment across diverse settings.

Legal implications

The sphere of what the law treats as private has shifted over time, often in response to changing technology and social practice. When the Supreme Court ruled in Olmstead v. United States that the police could wiretap phones without a warrant, telephony was not a particularly private medium. In 1928, calls required operator assistance, and operators could listen in. Party lines meant neighbors might share the same circuit. By 1967, when Katz v. United States reached the Court, the technology had transformed. Direct dialing had eliminated operators; party lines had largely disappeared. Telephony had become private, and the Court’s recognition of Fourth Amendment protection likely reflected that change.

Conversely, courts have also struggled to adapt existing doctrines built on assumptions about how physical barriers—walls, clothing, distance—protect privacy. In Kyllo v. United States (2001), the US Supreme Court held that thermal imaging of a home required a warrant because the technology allowed police to peer inside. Three years later, in R. v. Tessling, the Supreme Court of Canada reached the opposite conclusion, characterizing the same technology as merely observing heat signatures on the home’s surface “in a land of melting snow and spotty home insulation.” Justice Binnie cautioned, however, that the Court’s ruling applied to the technology as it then existed; improvements in resolution might warrant a different result.

None of these doctrinal shifts required exceptional technologies—only technologies that outpaced the assumptions underlying existing rules. Quantum sensing is no different, though its capabilities are far more invasive. Technologies that detect heartbeats through walls, reveal underground voids, or reconstruct keystrokes from electromagnetic emissions do not merely challenge the premises on which current doctrine depends—they threaten to render those premises obsolete.

Several modes of response are available. Courts will need to adapt legal doctrines as new facts demand, as they did from Olmstead to Katz and beyond. Legislatures can establish rules where common law development is too slow or uncertain. Regulatory agencies can participate in technical standard-setting, shaping how these technologies are built before they reach the market. Private actors—particularly the small number of sophisticated firms likely to develop quantum sensors—can condition access through robust human rights due diligence, restricting sales to end-users who demonstrate they will not deploy these tools for mass surveillance or other rights-violating purposes. And engineers can build privacy into the architecture itself, such as through resolution limits, audit logs, and use-case restrictions embedded in firmware.

Conclusion

Quantum technologies are advancing faster than ever. Coupled with the rise of AI, they will challenge our notions of privacy and create complex new risks. But quantum sensing does not fundamentally create new ethical or privacy concerns; rather, it accelerates and deepens existing threats. These technologies should not be treated as “exceptional,” because doing so could “alienate educators and create misconceptions about ways we can approach the consequential challenges,” as Rebecca Crootof and BJ Ard have argued.

Rather, quantum sensing has the potential to magnify privacy risks in ways that necessitate promoting industry standards, transparency, and legislation—alongside robust human rights due diligence by the firms developing these technologies. Awareness of this emerging field—and of the ways quantum technologies will reshape the privacy landscape—will better enable legal scholars and policymakers to address the risks ahead.

The authors wish to thank Michael Karanicolas.