Path: ...!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Martin Brown <'''newspam'''@nonad.co.uk> Newsgroups: sci.electronics.design Subject: Re: OT: Atomic nucleus excited with laser: a breakthrough after decades Date: Wed, 8 May 2024 12:52:27 +0100 Organization: A noiseless patient Spider Lines: 64 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 08 May 2024 13:52:30 +0200 (CEST) Injection-Info: dont-email.me; posting-host="b0be5a6b948c0c835723ed5fd0a03209"; logging-data="4147889"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19AEtyzwzX8fYImWq3TrWbeSmI0nEqxRacRS85NY1TP7A==" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:HqZ5q4f0We1AO0Sg/DfWFhrfDF4= Content-Language: en-GB In-Reply-To: Bytes: 3749 On 08/05/2024 09:44, Jeroen Belleman wrote: > On 5/8/24 01:36, John Larkin wrote: >> On Tue, 07 May 2024 12:17:24 -0400, Joe Gwinn >> wrote: >> >>> On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman >>> wrote: >>> >>>> On 5/7/24 15:35, Martin Brown wrote: >>>>> On 07/05/2024 06:06, Jan Panteltje wrote: >>>>>> Atomic nucleus excited with laser: a breakthrough after decades >>>>>>    >>>>>>     The 'thorium transition', which has been sought after for >>>>>> decades, >>>>>>     has now been excited for the first time with lasers. >>>>>>     This paves the way for revolutionary high precision technologies, >>>>>> including nuclear clocks >>>>> >>>>> I wonder what the Q value for stimulated nuclear emission is? >>>>> >>>> >>>> They state a centre frequency of roughly 2 PHz and a decay time >>>> of 630s, which would put the Q in the 1e19 ballpark. Prodigious. >>>> No wonder it was hard to find. >>> >>> The Time guys have been looking for this forever, so to speak. >>> >>> It's the only atomic kernel transition with any degree of coupling to >>> electromagnetic radiation.  This will be orders of magnitude better >>> than such as lattice clocks. >>> >>> There will be a flood of papers. >>> >>> Joe Gwinn >> >> They aren't tuning to a resonance, but to the difference between two >> close resonances. > > The current definition of the second uses something similar: Some > hyperfine resonance of cesium. Normal resonances are in the optical > domain, but hyperfine ones are RF. Which puts them in the RF frequency domain where counting cycles of the continuous sine reference waveform is relatively easy. Likewise for H-maser another favourite local time reference signal. > In nuclei, normal transitions are in the gamma domain, and > hyperfine ones are in the domain of optics. It's just a change > of scale, if you will. Although there will be some big practical difficulties counting cycles of a waveform at 8eV which is up into the UV. What is the current highest frequency that a semiconductor divider is capable of accepting? I know that there are some optical logic circuits about but how capable are they at near UV light? You can't mix this thing down without losing its fidelity. I know how to double optical frequencies but how do you halve or quarter them? -- Martin Brown