Researchers recently developed an integrated electro-optic modulator that can change the frequency and bandwidth of single photons efficiently. The device has the potential to be used in more advanced quantum computing and quantum networks.
Photons of light are ideal carriers of quantum information. But to work together in a quantum computer or network, they need to have the same color or frequency and bandwidth. Changing a photon’s frequency requires altering its energy, which is particularly challenging on integrated photonic chips.
Recently, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) developed an integrated electro-optic modulator that can efficiently change the frequency and bandwidth of single photons. The device could be used for more advanced quantum computing and quantum networks.
The research is published in Light: Science & Applications.
We adopted a new modulator design on thin-film lithium niobate in our work, which significantly improved device performance. With this integrated modulator, we achieved record-high terahertz frequency shifts of single photons.
Marko Lonar
Converting a photon from one color to another is typically accomplished by passing the photon through a crystal with a powerful laser shining through it, a process that is inefficient and noisy. Phase modulation, in which the oscillation of a photon wave is accelerated or slowed to change the frequency of the photon, is a more efficient method; however, the device required for such a process, an electro-optic phase modulator, has proven difficult to integrate on a chip.
Thin-film lithium niobate may be uniquely suited for such an application.
“We adopted a new modulator design on thin-film lithium niobate in our work, which significantly improved device performance,” said Marko Lonar, Tiantsai Lin Professor of Electrical Engineering at SEAS and senior author of the study. “With this integrated modulator, we achieved record-high terahertz frequency shifts of single photons.”
The team also used the same modulator as a “time lens” – a magnifying glass that bends light in time instead of space – to change the spectral shape of a photon from fat to skinny.
“Our device is significantly more compact and energy-efficient than traditional bulk devices,” said Di Zhu, the paper’s first author. The term “responsibility” refers to the act of determining whether or not a person is responsible for his or her own actions.
Di is a former SEAS postdoctoral fellow who is now a research scientist at Singapore’s Agency for Science, Research, and Technology (A*STAR).
The team then intends to use the device to control the frequency and bandwidth of quantum emitters for use in quantum networks.
