arXiv subjects

Chin-Wen Chou

Publications and source records attributed to Chin-Wen Chou.

4 recordsLinked to original sources

arXiv2025

High-fidelity quantum state control of a polar molecular ion in a cryogenic environment

We use a quantum-logic spectroscopy (QLS) protocol to control the quantum state of a CaH+ ion in a cryogenic environment, in which reduced thermal radiation extends rotational state lifetimes by an order of magnitude over those at room temperature. By repeatedly and adaptively probing the molecule, detecting the outcome of each probe via an atomic ion, and using a Bayesian update scheme to quantify confidence in the molecular state, we demonstrate state preparation and measurement (SPAM) in a single quantum state with infidelity less than 6x10^-3 and measure Rabi flopping between two states with greater than 99% contrast. The protocol does not require any molecule-specific lasers and the detection scheme is non-destructive.

physics.atom-ph↗

arXiv2022

Rotational spectroscopy of a single molecular ion at sub part-per-trillion resolution

We use quantum-logic spectroscopy (QLS) and interrogate rotational transitions of a single CaH+ ion with a highly coherent frequency comb, achieving a fractional statistical uncertainty for a transition line center of 4 x 10^-13. We also improve the resolution in measurement of the Stark effect due to the radio-frequency (rf) electric field experienced by a molecular ion in an rf Paul trap, which we characterize and model. This allows us to determine the electric dipole moment of CaH+ by systematically displacing the ion to sample different known rf electric fields and measuring the resultant shifts in transition frequency.

physics.atom-ph↗

arXiv2013

Absolute and relative stability of an optical frequency reference based on spectral hole burning in Eu$^{3+}$:Y$_2$SiO$_5$

We present and analyze four frequency measurements designed to characterize the performance of an optical frequency reference based on spectral hole burning in \EuYSO. The first frequency comparison, between a single unperturbed spectral hole and a hydrogen maser, demonstrates a fractional frequency drift rate of $5 \times 10^{-18}$ s$^{-1}$. Optical-frequency comparisons between a pattern of spectral holes, a Fabry-Pérot cavity, and an Al$^+$ optical atomic clock show a short-term fractional frequency stability of $1 \times10^{-15} τ^{-1/2}$ that averages down to $2.5^{+1.1}_{-0.5} \times 10^{-16}$ at $τ= 540~s$ (with linear frequency drift removed). Finally, spectral hole patterns in two different \EuYSO crystals located in the same cryogenic vessel are compared, yielding a short-term stability of $7 \times10^{-16} τ^{-1/2}$ that averages down to $5.5^{+1.8}_{-0.9} \times 10^{-17}$ at $τ= 204$~s (with quadratic frequency drift removed).

physics.atom-ph↗

arXiv2007

Functional Quantum Nodes for Entanglement Distribution over Scalable Quantum Networks

We demonstrate entanglement distribution between two remote quantum nodes located 3 meters apart. This distribution involves the asynchronous preparation of two pairs of atomic memories and the coherent mapping of stored atomic states into light fields in an effective state of near maximum polarization entanglement. Entanglement is verified by way of the measured violation of a Bell inequality, and can be used for communication protocols such as quantum cryptography. The demonstrated quantum nodes and channels can be used as segments of a quantum repeater, providing an essential tool for robust long-distance quantum communication.

quant-ph↗