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DECEMBER 2022 I DESIGN007 MAGAZINE 79 The Road Not Taken by Robert Frost Two roads diverged in a yellow wood, And sorry I could not travel both And be one traveler, long I stood And looked down one as far as I could To where it bent in the undergrowth; Then took the other, as just as fair, And having perhaps the better claim, Because it was grassy and wanted wear; Though as for that the passing there Had worn them really about the same, And both that morning equally lay In leaves no step had trodden black. Oh, I kept the first for another day! Yet knowing how way leads on to way, I doubted if I should ever come back. I shall be telling this with a sigh Somewhere ages and ages hence: Two roads diverged in a wood, and I— I took the one less traveled by, And that has made all the difference. DESIGN007 Joe Fjelstad is founder and CEO of Verdant Electronics and an international author- ity and innovator in the field of electronic interconnec- tion and packaging tech- nologies with more than 185 patents issued or pending. To read past columns or contact Fjelstad, click here. Down- load your copy of Fjelstad's book Flexible Circuit Technology, 4 th Edition, and watch his in-depth workshop series "Flexible Circuit Technology." Optical photons are ideal carriers of quantum infor- mation. But to work together in a quantum computer or network, they need to have the same color 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 modu- lator that can efficiently change the frequency and bandwidth of single photons. Converting a photon from one color to another is usually done by sending the photon into a crystal with a strong laser shining through it, a process that tends to be inefficient and noisy. Phase modulation, in which photon wave's oscillation is accelerated or slowed down to change the photon's frequency, offers a more efficient method, but the device required for such a process, an electro-optic phase modulator, has proven difficult to integrate on a chip. One material may be uniquely suited for such an application: thin-film lithium niobate. "In our work, we adopted a new modulator design on thin-film lithium niobate that significantly improved the device performance," said Marko Lončar, the Tiantsai Lin Professor of Electrical Engineering at SEAS and senior author of the study. "With this inte- grated modulator, we achieved record-high terahertz frequency shifts of single photons." Next, the team aims to use the device to control the frequency and bandwidth of quantum emitters for applications in quantum networks. (Source: Harvard John A. Paulson School of Engi- neering and Applied Sciences) Changing Color of Quantum Light on an IC