Sub-picosecond optical switching and amplification at the fundamental quantum limit at room temperature

[John Clark]

To those who claim that Moore's law is approaching its end I would point them to Wednesday's issue of the journal "Nature".  IBM researchers report they have developed an optical replacement for the transistor that operates at room temperature,  requires no cooling because it approaches the quantum theoretical limit on energy efficiency,  and is about 1000 times faster than any existing transistor. More work will be required before an entire microprocessor can be made using these devices but I find this development to be enormously encouraging.

The reason it's so energy efficient is that it only takes one photon from a very weak laser to switch a far more powerful laser on and off. And besides acting as a switch it can also act as an amplifier by boosting the intensity of a laser beam by a factor of 23,000.

Single-photon nonlinearity at room temperature

John K Clark    See what's on my new list at  Extropolis

42h

[spudb...@aol.com]

Plus, it takes no liquid helium or nitrogen levels to bring these beauties into action and production. QC is arriving, but I would have figured that it digital computing would have vanished, rather than be roaring ahead with massive innovations.

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[Lawrence Crowell]

I am curious by what is meant by a single photon being nonlinear. I could not find this on arxiv.

LC

[John Clark]

On Fri, Sep 24, 2021 at 10:21 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> I am curious by what is meant by a single photon being nonlinear. I could not find this on arxiv.

If this explanation is incorrect, blame me and not the authors of the article. But if I'm reading them correctly they use that term because they used a pump laser to produce a population inversion in the laser microcavity with the higher vibrational energy being exactly one quantum level above the other.  They could control it so precisely that when they increased the excitation density of the micro resonating chamber by just one photon the entire laser transitioned from the linear to the nonlinear regime. They found that due to the material used there was a wide spread in the momentum distribution of the exciton, so the  n-plane momentum component of the trigger photon was not important, only the energy level of the photon was.

John K Clark    See what's on my new list at  Extropolis

uoo

42h

[James Wright]

On Saturday, September 25, 2021 at 1:46:01 PM UTC+2 johnk...@gmail.com wrote:

On Fri, Sep 24, 2021 at 10:21 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> I am curious by what is meant by a single photon being nonlinear. I could not find this on arxiv.

If this explanation is incorrect, blame me and not the authors of the article. But if I'm reading them correctly they use that term because they used a pump laser to produce a population inversion in the laser microcavity with the higher vibrational energy being exactly one quantum level above the other.  They could control it so precisely that when they increased the excitation density of the micro resonating chamber by just one photon the entire laser transitioned from the linear to the nonlinear regime. They found that due to the material used there was a wide spread in the momentum distribution of the exciton, so the  n-plane momentum component of the trigger photon was not important, only the energy level of the photon was.

The goal are things like all optical computers/devices. Capabilities such as switching,  amplification, cascading, all optical logic require a substrate to mediate the interaction. Light doesn't interact with light in a pure vacuum obviously. Not in a way that is quickly switchable. Non-linear properties of hybrid light-matter condensates operating with lasers are called for. That Pump laser produces a large population of hot excitons which is relaxed back to polariton ground state. Sub-picosecond all-optical switching is reached by the combination of ultrafast exciton relaxation dynamics of organic semiconductors, and the sub-picosecond cavity lifetime of their setups. It's not the photon or laser that is nonlinear. 

The photon induces switching of the hybrid light-matter states of the exciton polariton condensates sandwiched between mirrors in the cavity. That high speed operability harnesses non-linearity of the condensate with lasers. Tiny photon seems to exploit even polariton-polariton interaction. One photon to flip a switch is extremely efficient. If this is what it seems, then battery draining of more powerful devices operating on way less power may happen. More power, speed, and environmentally friendly to boot? Our phones and computers are perhaps wasteful trash. 

James W.