Dongchel Shin

Research

Quantum & Precision Metrology

I work across theory and experiment. Starting from first principles, I find what fundamentally limits a system, then build what it takes to reach that limit: the optics, mechanics, and electronics, and the control and instrumentation that tie them together.

Macroscopic Quantum Mechanics

A feedback loop (oscillator, measurement, filter, actuation) beside the oscillator's energy ladder, with thermal occupation collapsing toward the ground level as it cools

Whether gravity obeys quantum mechanics remains an open question, and testing it requires an object massive enough to gravitate yet prepared in a quantum state. I work toward this goal by cooling a centimeter-scale torsional oscillator toward its quantum ground state with quantum-limited optical measurement and feedback. Moreover, such a system probes quantum mechanics at unprecedented mass scales and senses forces and displacements at the limit set by quantum noise.

Related publications

  • D.-C. Shin, T. M. Hayward, D. Fife, R. Menon, V. Sudhir, “Active laser cooling of a centimeter-scale torsional oscillator,” Optica (2025)
  • D. Fife, D.-C. Shin, V. Sudhir, “Temperature stabilization of a lab space at 10 mK-level over a day,” Rev. Sci. Instrum. (2024)

Theoretical Tools for Quantum Metrology

A phase-squeezed state in phase space, and two photons at the sidebands of a laser joined by an infinity-shaped loop to show their entanglement

Real optical measurements use light spread across many frequencies and spatial modes, so their quantum noise must be understood within multimode quantum optics. I develop first-principles theory that predicts the fundamental limits of practical measurement schemes and shows how to surpass them. In this picture, engineered multimode quantum states of light, such as squeezed and entangled light, become new metrological resources.

Related publications

  • D.-C. Shin, E. Ng, M.-G. Suh, V. Sudhir, “Continuum-field quantum optics of frequency comb metrology,” arXiv (2026)

Frequency Comb Metrology

An optical pulse train in time and its Fourier transform, a frequency comb whose lines sit at n times the repetition rate plus the carrier-envelope offset

An optical frequency comb links optical frequencies to the microwave and terahertz domains, so the stability of the best optical references can be carried into other frequency bands and instruments. I use combs to synthesize ultra-stable terahertz signals, to synchronize independent combs at the hertz level, and to build precision measurements on them.

Related publications

  • D.-C. Shin, J. Yang, D. I. Lee, G. Kang, S.-W. Kim, Y.-J. Kim, “Compact, robust all-fiber platform for 1-Hz-linewidth synchronization of optical frequency combs using single comb line extraction,” Optics & Laser Technology (2026)
  • G. Kang, J. Kim, M.-R. Kim, Y. Lee, D.-C. Shin, J. Jeon, H. Kim, D. H. Kim, J. Lee, S. Park, Y.-J. Kim, “Nanometre-precision terahertz interferometry for battery electrode metrology,” Nature Communications (2026)
  • M.-G. Suh, D. Dang, M. Gao, Y. Jin, D.-C. Shin, A. Gupta, B. J. Park, C. Uzundal, B. Hu, W. J. M. Kort-Kamp, H. W. H. Lee, “Hyperspectral dual-comb compressive ghost imaging with deep learning reconstruction,” Light: Science & Applications (2026)
  • D.-A. Nguyen, D. H. Kim, G. H. Lee, S. Kim, D.-C. Shin, J. Park, H.-J. Choi, S.-W. Kim, S. Kim, Y.-J. Kim, “Real-time monitoring of fast gas dynamics with a single-molecule resolution by frequency-comb-referenced plasmonic phase spectroscopy,” PhotoniX (2024)
  • D.-C. Shin, B. S. Kim, H. Jang, Y.-J. Kim, S.-W. Kim, “Photonic comb-rooted synthesis of ultra-stable terahertz frequencies,” Nature Communications (2023)
  • J. Yang, D. I. Lee, D.-C. Shin, J. Lee, B. S. Kim, H. J. Kang, Y.-J. Kim, S.-W. Kim, “Frequency comb-to-comb stabilization over a 1.3-km free-space atmospheric optical link,” Light: Science & Applications (2022)