paper / rainerblatt / Mar 8
Spectral crowding from collective motional modes causes off-resonant coupling that degrades entangling gate fidelity in multi-ion trapped-ion quantum processors. A geometric-phase gate driven by transverse time-dependent structured-light forces in the plane orthogonal to beam propagation mitigates this by reducing spectator mode crosstalk while maintaining single-ion addressability. Demonstrated with error rates below 5e-3 for two-qubit gates in up to 12-ion crystals sharing a single potential well, compatible with any qubit encoding showing differential AC Stark shifts.
quantum-physicsquantum-computingtrapped-ion-systemsentanglementlight-gradientshigh-fidelity-gates
“Spectral crowding of collective motional modes limits entangling interaction fidelity via off-resonant coupling to spectator modes.”
paper / rainerblatt / Nov 6
This paper introduces a novel method for robustly certifying the non-simulability of Positive Operator-Valued Measures (POVMs) by projective measurements. The approach utilizes a hierarchy of semidefinite programs to establish tight upper bounds on the critical visibility, thus distinguishing advantages offered by general quantum measurements. The framework is experimentally validated on trapped-ion qudit quantum processors for two- and three-dimensional POVMs and includes modifications for robustness against state preparation errors, with extensions for ancilla systems.
quantum-measurementspovmsprojective-measurementsquantum-computingtrapped-ion-processorssemidefinite-programmingquantum-information
“Determining when POVMs outperform projective measurements is a challenging and unresolved problem.”
paper / rainerblatt / Oct 9
This paper introduces motional spin-locking spectroscopy, a novel method for directly measuring the motional noise spectrum of a quantum harmonic oscillator. This technique is demonstrated experimentally on a single trapped ion, achieving high sensitivity in a relevant frequency range. This advancement is crucial for optimizing quantum computing platforms by enabling precise noise characterization.
quantum-physicsquantum-harmonic-oscillatormotional-noisespin-locking-spectroscopytrapped-ionsquantum-measurement
“Motional spin-locking spectroscopy can directly measure the motional noise spectrum of a quantum harmonic oscillator.”
paper / rainerblatt / May 27
This work introduces a multi-metal layer ion trap fabricated on a fused silica substrate, addressing critical challenges in scaling ion trap devices for quantum computing. The design focuses on minimizing power dissipation, a significant improvement over silicon-based traps. The research validates functionality down to 10 K and demonstrates improved trap performance through detailed characterization of electric field noise and stray fields using a single trapped ion probe.
quantum-computingion-trapsquantum-hardwarefused-silicacryogenicsquantum-engineering
“Multi-metal layer ion traps on fused silica substrates reduce power dissipation compared to silicon-based traps.”