Person: Zhang, Mian
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Zhang
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Mian
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Zhang, Mian
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Publication Electronically programmable photonic molecule(Springer Science and Business Media LLC, 2018-12-14) Zhang, Mian; Wang, Cheng; Hu, Yaowen; Shams Ansari, Amirhassan; Ren, Tianhao; Fan, Shanhui; Loncar, MarkoPhysical systems with discrete energy levels are ubiquitous in nature and are fundamental building blocks of quantum technology. Realizing controllable artificial atom- and molecule-like systems for light would enable coherent and dynamic control of the frequency, amplitude and phase of photons. In this work, we demonstrate a ‘photonic molecule’ with two distinct energy levels using coupled lithium niobate microring resonators and control it by external microwave excitation. We show that the frequency and phase of light can be precisely controlled by programmed microwave signals, using concepts of canonical two-level systems including Autler–Townes splitting, Stark shift, Rabi oscillation and Ramsey interference. Through such coherent control, we show on-demand optical storage and retrieval by reconfiguring the photonic molecule into a bright–dark mode pair. These results of dynamic control of light in a programmable and scalable electro-optic system open doors to applications in microwave signal processing, quantum photonic gates in the frequency domain and exploring concepts in optical computing8 and topological physics.Publication Real-time vibrations of a carbon nanotube(Springer Nature, 2019-01-21) Barnard, Arthur W.; Zhang, Mian; Wiederhecker, Gustavo S.; Lipson, Michal; McEuen, Paul L.The field of miniature mechanical oscillators is rapidly evolving, with emerging applications including signal processing, biological detection and fundamental tests of quantum mechanics. As the dimensions of a mechanical oscillator shrink to the molecular scale, such as in a carbon nanotube resonator, their vibrations become increasingly coupled and strongly interacting, until even weak thermal fluctuations could make the oscillator nonlinear. The mechanics at this scale possesses rich dynamics, unexplored because an efficient way of detecting the motion in real time is lacking. Here we directly measure the thermal vibrations of a carbon nanotube in real time using a high-finesse micrometre-scale silicon nitride optical cavity as a sensitive photonic microscope. With the high displacement sensitivity of 700 fm Hz-1/2 and the fine time resolution of this technique, we were able to discover a realm of dynamics undetected by previous time-averaged measurements and a room-temperature coherence that is nearly three orders of magnitude longer than previously reported. We find that the discrepancy in the coherence stems from long-time non-equilibrium dynamics, analogous to the Fermi-Pasta-Ulam-Tsingou recurrence seen in nonlinear systems. Our data unveil the emergence of a weakly chaotic mechanical breather, in which vibrational energy is recurrently shared among several resonance modes-dynamics that we are able to reproduce using a simple numerical model. These experiments open up the study of nonlinear mechanical systems in the Brownian limit (that is, when a system is driven solely by thermal fluctuations) and present an integrated, sensitive, high-bandwidth nanophotonic interface for carbon nanotube resonators.Publication On-chip electro-optic frequency shifters and beam splitters(Springer Science and Business Media LLC, 2021-11-24) Hu, Yaowen; Yu, Mengjie; Shams Ansari, Amirhassan; Sinclair, Neil; Holzgrafe, Jeffrey; Puma, Eric; Zhang, Mian; Shao, Linbo; Loncar, MarkoEfficient frequency shifting and beam splitting is important for a wide range of applications, including atomic physics1,2, microwave photonics3–6, optical communication7,8, and photonic quantum computing9–14. However, realizing gigahertz-scale frequency shifts with high efficiency, low loss, and tunability, in particular using a miniature and scalable device, is challenging since it requires efficient and controllable nonlinear processes. Existing approaches based on acousto-optics6,15–17, all-optical wave mixing10,13,18–22, and electro-optics23–27 are either limited to low efficiencies or frequencies, or are bulky. Furthermore, most approaches are not bi-directional, which renders them unsuitable for frequency beam splitters. Here we demonstrate electro-optic frequency shifters that are controlled using only continuous and single-tone microwaves. This is accomplished by engineering the density of states of, and coupling between, optical modes in ultra-low loss waveguides and resonators in lithium niobate nanophotonics28. Our devices, consisting of two coupled-ring-resonators, provide frequency shifts as high as 28 GHz with an ~90% on-chip conversion efficiency. Importantly, the devices can be reconfigured as tunable frequency-domain beam splitters. Using the device, we also demonstrate a non-blocking and efficient swap of information between two frequency channels. Finally, we propose and demonstrate a scheme for cascaded frequency shifting that allows shifts of ~120 GHz using a ~30 GHz continuous and single-tone microwave signal. Our devices could become building-blocks for future high-speed and large-scale classical information processors7,29 as well as emerging frequency-domain photonic quantum computers9,11,14.Publication Quantum interference between transverse spatial waveguide modes(Nature Publishing Group, 2017) Mohanty, Aseema; Zhang, Mian; Dutt, Avik; Ramelow, Sven; Nussenzveig, Paulo; Lipson, MichalIntegrated quantum optics has the potential to markedly reduce the footprint and resource requirements of quantum information processing systems, but its practical implementation demands broader utilization of the available degrees of freedom within the optical field. To date, integrated photonic quantum systems have primarily relied on path encoding. However, in the classical regime, the transverse spatial modes of a multi-mode waveguide have been easily manipulated using the waveguide geometry to densely encode information. Here, we demonstrate quantum interference between the transverse spatial modes within a single multi-mode waveguide using quantum circuit-building blocks. This work shows that spatial modes can be controlled to an unprecedented level and have the potential to enable practical and robust quantum information processing.Publication Broadband electro-optic frequency comb generation in a lithium niobate microring resonator(Springer Nature, 2019-03-11) Zhang, Mian; Wang, Cheng; Shams-Ansari, Amirhassan; Reimer, Christian; Zhu, Rongrong; Loncar, MarkoOptical frequency combs consist of equally spaced discrete optical frequency components and are essential tools for optical communication, precision metrology, timing and spectroscopy1–9. To date, wide-spanning combs are most often generated by mode-locked lasers10 or dispersion-engineered resonators with third-order Kerr nonlinearity11. An alternative comb generation method uses electro-optic (EO) phase modulation in a resonator with strong second-order nonlinearity, resulting in combs with excellent stability and controllability12–14. Previous EO combs, however, have been limited to narrow widths by a weak EO interaction strength and a lack of dispersion engineering in free-space systems. In this work, we overcome these limitations by realizing an integrated EO comb generator in a thin-film lithium niobate (LN) photonic platform that features a large EO response, ultra-low optical loss and highly co-localized microwave and optical fields15, while enabling dispersion engineering. Our measured EO frequency comb spans more than the entire telecommunications L-band (over 900 comb lines spaced at ~ 10 GHz), and we show that future dispersion engineering can enable octave-spanning combs. Furthermore, we demonstrate the high tolerance of our comb generator to modulation frequency detuning, with frequency spacing finely controllable over seven orders of magnitude (10 Hz to 100 MHz), and utilize this feature to generate dual frequency combs in a single resonator. Our results show that integrated EO comb generators, capable of generating wide and stable comb spectra, are a powerful complement to integrated Kerr combs, enabling applications ranging from spectroscopy16 to optical communications8.Publication Controlling the coherence of a diamond spin qubit through its strain environment(Nature Publishing Group UK, 2018) Sohn, Young-Ik; Meesala, Srujan; Pingault, Benjamin; Atikian, Haig; Holzgrafe, Jeffrey; Gündoğan, Mustafa; Stavrakas, Camille; Stanley, Megan J.; Sipahigil, Alp; Choi, Joonhee; Zhang, Mian; Pacheco, Jose L.; Abraham, John; Bielejec, Edward; Lukin, Mikhail; Atatüre, Mete; Loncar, MarkoThe uncontrolled interaction of a quantum system with its environment is detrimental for quantum coherence. For quantum bits in the solid state, decoherence from thermal vibrations of the surrounding lattice can typically only be suppressed by lowering the temperature of operation. Here, we use a nano-electro-mechanical system to mitigate the effect of thermal phonons on a spin qubit – the silicon-vacancy colour centre in diamond – without changing the system temperature. By controlling the strain environment of the colour centre, we tune its electronic levels to probe, control, and eventually suppress the interaction of its spin with the thermal bath. Strain control provides both large tunability of the optical transitions and significantly improved spin coherence. Finally, our findings indicate the possibility to achieve strong coupling between the silicon-vacancy spin and single phonons, which can lead to the realisation of phonon-mediated quantum gates and nonlinear quantum phononics.