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Ultrasecure. Researchers at Boston University, Harvard, and BBN Technologies (the company that developed ARPANET, the precursor to the Internet) are using a new quantum cryptography computer network to send information with such ultratight security that even the most subtle eavesdropping immediately alerts administrators to the security leak and automatically stops the flow of information.

The BU researchers who developed this system include Alexander Sergienko, Malvin Teich, and Bahaa Saleh, College of Engineering professors of electrical and computer engineering, Gregg Jaeger, a CGS assistant professor of natural science, and Hugues De Chatellus and Gianni Di Giuseppe, ENG research associates. The six-node quantum cryptography network they helped build uses light particles, called photons, as keys to encrypt the information before it is sent and to decipher it at the receiver end.

The system depends on one of the basic assumptions of quantum physics — that subatomic particles, like photons, can exist in multiple states at the same time until something interacts with them. Thus, an interloper trying to observe the photons as they are being transmitted changes them, both destroying the code and making it apparent that the system has been compromised.

Although the Boston network is still small, with only six nodes, two in each of three locations, it is believed to be the first Internet-integrated system to run continuously between multiple distant locations. The network currently uses photons produced by heavily filtered lasers. The BU team is working to replace these with entangled photon pairs, which would be more efficient.

Quantum cryptography is a modern descendant of a system used during Word War II, where spies in different locations used identical code books. The page number of the code to be used, the key, was transmitted separately from the transmission to be decoded. Understanding the encrypted material depended upon having the correct key.

Insecure. U.S. immigration policies that prevent women on spousal visas from working or petitioning on their own for a change of visa status put them at risk for sexual and physical abuse by their partners, according to a new study by Anita Raj, an SPH assistant professor of social and behavioral sciences.

Raj and her colleagues surveyed 189 married immigrant South Asian women, gathering information about demographics, immigration status, and health. They asked about immigration-related partner abuse — such as threats of deportation, refusal to file for change of visa status, and not allowing access to immigration paperwork — as well as about intimate partner violence. The team also conducted in-depth interviews with immigrant South Asian women with a history of such violence.

The study focused on people from India, the largest South Asian group in the United States, comprising nearly 50 percent of those receiving H-1B visas, which are work visas granted primarily to professionals. Holders of an H-1B visa can convert to legal permanent resident status by acquiring a green card with the sponsorship of their employers. Spouses of H-1B visa holders are given H-4B visas, which legally permit them to be in this country, but prohibit them from obtaining paid employment. The law requires that H-1B holders petition for green card status. It also prohibits H-4B holders from getting a social security card, which prevents them from opening a bank account or obtaining a driver’s license and keeps them economically and legally dependent on their spouse.

The researchers found that even among high-income and highly educated women, those with partner-dependent visa status were more likely than those with other immigrant status (work visa holders, green card holders, and U.S. citizens) to report physical or sexual violence from their husbands. Deportation threats and refusal to file for change of status were also significantly related to physical abuse and sexual abuse. The interviews revealed that batterers prevent access to immigration documents as part of a strategy to control their spouses.

“Overall,” the researchers say, “our findings demonstrate the need for policy changes that would allow women coming to the U.S. under spousal dependent visas to become employed and to self-petition for a change in visa status if they choose.”

This paper will appear in the October 8 issue of the Journal of the American Medical Women’s Association.

"Research Briefs" is written by Joan Schwartz in the Office of the Provost. To read more about BU research, visit


15 May 2003
Boston University
Office of University Relations