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- Higgins, Gerard, 1989, et al.
(författare)
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Micromotion minimization using Ramsey interferometry
- 2021
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 23:12
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Tidskriftsartikel (refereegranskat)abstract
- We minimize the stray electric field in a linear Paul trap quickly and accurately, by applying interferometry pulse sequences to a trapped ion optical qubit. The interferometry sequences are sensitive to the change of ion equilibrium position when the trap stiffness is changed, and we use this to determine the stray electric field. The simplest pulse sequence is a two-pulse Ramsey sequence, and longer sequences with multiple pulses offer a higher precision. The methods allow the stray field strength to be minimized beyond state-of-the-art levels. Using a sequence of nine pulses we reduce the 2D stray field strength to (10.5 +/- 0.8) mV m(-1) in 11 s measurement time. The pulse sequences are easy to implement and automate, and they are robust against laser detuning and pulse area errors. We use interferometry sequences with different lengths and precisions to measure the stray field with an uncertainty below the standard quantum limit. This marks a real-world case in which quantum metrology offers a significant enhancement. Also, we minimize micromotion in 2D using a single probe laser, by using an interferometry method together with the resolved sideband method; this is useful for experiments with restricted optical access. Furthermore, a technique presented in this work is related to quantum protocols for synchronizing clocks; we demonstrate these protocols here.
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| 2. |
- Higgins, Gerard, et al.
(författare)
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Observation of second- and higher-order electric quadrupole interactions with an atomic ion
- 2021
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Ingår i: Physical Review Research. - 2643-1564. ; 3:3
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Tidskriftsartikel (refereegranskat)abstract
- The response of matter to fields underlies the physical sciences, from particle physics to astrophysics, and from chemistry to biophysics. We observe an atom's response to an electric quadrupole field to second- and higher orders; this arises from the atom's electric quadrupole polarizability and hyperpolarizabilities. We probe a single atomic ion which is excited to Rydberg states and confined in the electric fields of a Paul trap. The quadrupolar trapping fields cause atomic energy level shifts and give rise to spectral sidebands. The observed effects are described well by theory calculations.
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| 3. |
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| 4. |
- Salim, Shalina
(författare)
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Towards a high fidelity Rydberg interaction gate
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Trapped Rydberg ions with their extraordinary properties serve as very good candidatesfor quantum computing and quantum simulation. The strong dipole-dipoleinteraction in Rydberg ions enables fast entangling gates between qubits. The entanglementdoes not involve motional quantum state to exchange information, whichmakes it suitable to perform gate operations in a long ion string. In this report,preliminary studies for cooling the trapped ions using polarization gradient coolingand addressing of single ion in a long ion string have been done. The results showthat for cooling of multiple ions in a linear chain, a combination of Doppler coolingand polarization gradient cooling provides better cooling as compared to Dopplercooling alone. Simulations for single ion addressing shows that the focusing of thebeams on the ions can be further improved by using additional optics described bythe simulation. Better focusing is essential to deliver higher laser intensities to theion such that the Rabi frequency is higher. This is important for improving the delity of gate operation in long ion strings.
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