Single-chip photonic deep neural network with forward-only training
nature.com
nature.com
> Here we realize such a system in a scalable photonic integrated circuit that monolithically integrates multiple coherent optical processor units for matrix algebra and nonlinear activation functions into a single chip. We experimentally demonstrate this fully integrated coherent optical neural network architecture for a deep neural network with six neurons and three layers that optically computes both linear and nonlinear functions [...]
> This work lends experimental evidence to theoretical proposals for in situ training, enabling orders of magnitude improvements in the throughput of training data. Moreover, the fully integrated coherent optical neural network opens the path to inference at nanosecond latency and femtojoule per operation energy efficiency.
From "Transistor for fuzzy logic hardware: promise for better edge computing" https://news.ycombinator.com/item?id=42166303 :
> From "A carbon-nanotube-based tensor processing unit" (2024) https://www.nature.com/articles/s41928-024-01211-2 :
>> Using system-level simulations, we estimate that an 8 bit TPU made with nanotube transistors at a 180 nm technology node could reach a main frequency of 850 MHz and an energy efficiency of 1 tera-operations per second per watt.
Performance per watt: https://en.wikipedia.org/wiki/Performance_per_watt
> 5nm process
Notes from "Single atom defect in 2D material can hold quantum information at room temp" (2024) https://news.ycombinator.com/item?id=40478219 re Qubit data storage (quantum wave transmission through spacetime)
"Reversible optical data storage below the diffraction limit" (2024) https://news.ycombinator.com/item?id=38528877 :
> multiplexing Diamond with different color beams , "Real-space nanophotonic field manipulation using non-perturbative light–matter coupling" (2023) ; below the Abbe diffraction limit optional tweezers at 1/50 the photonic wavelength
"DNA-folding nanorobots can manufacture limitless copies of themselves" https://news.ycombinator.com/item?id=38569474
Phase from Intensity because Huygens' classical oscillatory model applies to photons;
From "Physicists use a 350-year-old theorem to reveal new properties of light waves" https://news.ycombinator.com/item?id=37226160 :
>> [..] Qian's team interpreted the intensity of a light as the equivalent of a physical object's mass, then mapped those measurements onto a coordinate system that could be interpreted using Huygens' mechanical theorem. "Essentially, we found a way to translate an optical system so we could visualize it as a mechanical system, then describe it using well-established physical equations," explained Qian.
>> Once the team visualized a light wave as part of a mechanical system, new connections between the wave's properties immediately became apparent—including the fact that entanglement and polarization stood in a clear relationship with
"Bridging coherence optics and classical mechanics: A generic light polarization-entanglement complementary relation" (2023) https://journals.aps.org/prresearch/abstract/10.1103/PhysRev... :
> Abstract: [...] Here we report links of the two through a systematic quantitative analysis of polarization and entanglement, two optical coherence properties under the wave description of light pioneered by Huygens and Fresnel. A generic complementary identity relation is obtained for arbitrary light fields. More surprisingly, through the barycentric coordinate system, optical polarization, entanglement, and their identity relation are shown to be quantitatively associated with the mechanical concepts of center of mass and moment of inertia via the Huygens-Steiner theorem for rigid body rotation. The obtained result bridges coherence wave optics and classical mechanics through the two theories of Huygens.
/?hnlog coherent , single photon
[...]
"Photonic quantum Hall effect and multiplexed light sources of large orbital angular momenta (2021) https://www.nature.com/articles/s41567-021-01165-8 .. https://engineering.berkeley.edu/news/2021/02/light-unbound-... :
"Coherent interaction of a-few-electron quantum dot with a terahertz optical resonator" (2023) https://arxiv.org/abs/2204.10522 .. https://news.ycombinator.com/item?id=39365579
From https://news.ycombinator.com/item?id=39287722 :
> "Room-temperature quantum coherence of entangled multiexcitons in a metal-organic framework" (2024) https://www.science.org/doi/10.1126/sciadv.adi3147
> "A physical [photonic] qubit with built-in error correction" (2024) https://news.ycombinator.com/item?id=39243929
> What about phononic quantum computing though, are phononic wave functions stable/coherent?
From "Electrons become fractions of themselves in graphene, study finds" (2024) re: the electronic fractional quantum Hall effect without magnetic fields https://news.mit.edu/2024/electrons-become-fractions-graphen... :
> They found that when five sheets of graphene are stacked like steps on a staircase, the resulting structure inherently provides just the right conditions for electrons to pass through as fractions of their total charge, with no need for any external magnetic field.
"Fractional quantum anomalous Hall effect in multilayer graphene" (2024) https://www.nature.com/articles/s41586-023-07010-7
"How can electrons split into fractions of themselves?" https://news.mit.edu/2024/how-can-electrons-can-split-into-f... ... Re: why pentalayer
What was the SNL number of safety razer blades skit?
In rhombohedral trilayer graphene, there is superconductivity at one or more phases;
"Revealing the complex phases of rhombohedral trilayer graphene" (2024) https://www.nature.com/articles/s41567-024-02561-6 .. https://news.ycombinator.com/item?id=40919269
"Revealing the superconducting limit of twisted bilayer graphene" https://news.ycombinator.com/item?id=42051367 :
"Low-Energy Optical Sum Rule in Moiré Graphene" (2024) https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.13... https://arxiv.org/abs/2312.03819
"Large quantum anomalous Hall effect in spin-orbit proximitized rhombohedral graphene" (2024) https://www.science.org/doi/10.1126/science.adk9749
"Physicists spot quantum tornadoes twirling in a ‘supersolid’" (2024) https://news.ycombinator.com/item?id=42082690
Correction:
Phase from second-order Intensity due to "mechanical concepts of center of mass and moment of inertia via the Huygens-Steiner theorem for rigid body rotation"
Parallel axis theorem: https://en.wikipedia.org/wiki/Parallel_axis_theorem :
> The parallel axis theorem, also known as Huygens–Steiner theorem, or just as Steiner's theorem, [1] named after Christiaan Huygens and Jakob Steiner, can be used to determine the moment of inertia or the second moment of area of a rigid body about any axis, given the body's moment of inertia about a parallel axis through the object's center of gravity and the perpendicular distance between the axes.
( Huygens-Fresnel principle > Generalized Huygens' principle > and quantum field theory: https://en.wikipedia.org/wiki/Huygens%E2%80%93Fresnel_princi... :
> [ Kirchoff, Path Integrals (Hamilton, Lorentz, Feynmann,), quabla operator and Minkowski space, Secondary waves and superposition; ]
> Homogeneity of space is fundamental to quantum field theory (QFT) where the wave function of any object propagates along all available unobstructed paths. When integrated along all possible paths, with a phase factor proportional to the action, the interference of the wave-functions correctly predicts observable phenomena. Every point on the wavefront acts as the source of secondary wavelets that spread out in the light cone with the same speed as the wave. The new wavefront is found by constructing the surface tangent to the secondary wavelets.
Lorentz oscillator model > See also: https://en.wikipedia.org/wiki/Lorentz_oscillator_model )