Abstract

A rapidly reprogrammable neural network architecture with the possibility for a large synapse matrix is presented. The concept is based on the use of bacteriorhodopsin as a molecular computational element with electrooptical characteristics that are associated with a series of intermediates that are photochemically initiated. One of these states has been stabilized by several orders of magnitude with specific environmental conditions, and this allows the concentration of intermediates to be readily affected without the need for continuous holding illuminations. Thus, the photoelectrical characteristics at each synapse can readily be modulated, and a scheme has been devised to read the synaptic matrix without erasing the impressed synaptic strengths. Electrical measurements are presented to test specific aspects of the overall neural network implementation, and the results of these measurements are encouraging for the development of such a distinctive neural network device.

© 1991 Optical Society of America

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References

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  1. L. P. Packer, Ed., Methods in Enzymology, Vol. 88 (Academic, New York, 1982).
  2. G. I. Groma, G. Szabo, G. Varo, “Direct Measurement of Picosecond Charge Separation in Bacteriorhodopsin,” Nature London 308, 577–558 (1984).
    [Crossref]
  3. E. Ippen, C. V. Shank, A. Lewis, M. Marcus, “Subpicosecond Spectroscopy of Bacteriorhodopsin,” Science200, 1279–1281 (1978); ;M. C. Downer, M. Islam, C. V. Shank, A. Harootunian, A. Lewis, “Title,” in Ultrafast Phonomena IV, D. H. Austin, K. B. Eisenthal, Eds. (Springer-Verlag, Berling, 1984).
    [Crossref]
  4. H. J. Polland, M. A. Franz, W. Zenith, W. Kaiser, E. Kolling, D. Oersterhelt, “Femtosecond Photochemistry of Bacteriorhodopsin,” Biophys. J. 49, 651–662 (1986); ;R. A. Mathies, C. H. Brito Cruz, W. T. Pollard, C. V. Shank, “Direct Observation of the Femtosecond Excited-State cis-trans Isomerization in Bacteriorhodopsin,” Science 240, 777–779 (1988).
    [Crossref] [PubMed]
  5. Z. Chen, A. Lewis, H. Takei, I. Nebenzahl, “BR Oriented in Polyvinylalcohol Films as an Erasable Optical Storage Medium,” submitted for publication.
  6. N. N. Vsevolodov, V. A. Poltoratski, “Holograms in Biochrome, a Biological Photochromic Material,” Sov. Phys. Tech. Phys. 30, 1235 (1985).
  7. N. N. Vsebolodov, G. R. Ivanitsky, “Biological Photosensory Complexes as Technical Information Carriers,” Biofizika 30, 884–887 (1985).
  8. O. Kalisky, U. Lachish, M. Ottolenghi, “Time Resolution of a Back Photoreaction in Bacteriorhodopsin,” Photochem. Photobiol. 28, 261–263 (1978).
    [Crossref]
  9. B. Becher, T. G. Ebrey, “The Quantum Efficiency for the Photochemical Conversion of the Purple Membrane Protein,” Biophys. J. 17, 185–191 (1977).
    [Crossref] [PubMed]
  10. D. Oesterhelt, W. Stoeckenius, “Isolation of the Cell Membrane of Halobacterium halobium and its Fractionation in the Red and Purple Membrane,” Methods Enzymol. 31, 667–678 (1974).
    [Crossref] [PubMed]
  11. G. Varo, “Dried Oriented Purple Membrane Samples,” Acta Biol. Acad. Sci. Hung. 32, 301–310 (1982).
  12. H. Takei, A. Lewis, Z. Chen, I. Nebenzahl, “Implementing receptive fields with excitatory and inhibitory optoelectrical responses of bacteriorhodopsin films,” Applied Optics, 30, 500–509 (1991).
    [Crossref] [PubMed]
  13. A. Fahr, P. Lauger, E. Bamberg, “Photocurrent Kinetics of Purple-Membrane Sheets Bound to Planar Bilayer Membranes,” J. Membrane Biol. 60, 51–62 (1981).
    [Crossref]

1991 (1)

H. Takei, A. Lewis, Z. Chen, I. Nebenzahl, “Implementing receptive fields with excitatory and inhibitory optoelectrical responses of bacteriorhodopsin films,” Applied Optics, 30, 500–509 (1991).
[Crossref] [PubMed]

1986 (1)

H. J. Polland, M. A. Franz, W. Zenith, W. Kaiser, E. Kolling, D. Oersterhelt, “Femtosecond Photochemistry of Bacteriorhodopsin,” Biophys. J. 49, 651–662 (1986); ;R. A. Mathies, C. H. Brito Cruz, W. T. Pollard, C. V. Shank, “Direct Observation of the Femtosecond Excited-State cis-trans Isomerization in Bacteriorhodopsin,” Science 240, 777–779 (1988).
[Crossref] [PubMed]

1985 (2)

N. N. Vsevolodov, V. A. Poltoratski, “Holograms in Biochrome, a Biological Photochromic Material,” Sov. Phys. Tech. Phys. 30, 1235 (1985).

N. N. Vsebolodov, G. R. Ivanitsky, “Biological Photosensory Complexes as Technical Information Carriers,” Biofizika 30, 884–887 (1985).

1984 (1)

G. I. Groma, G. Szabo, G. Varo, “Direct Measurement of Picosecond Charge Separation in Bacteriorhodopsin,” Nature London 308, 577–558 (1984).
[Crossref]

1982 (1)

G. Varo, “Dried Oriented Purple Membrane Samples,” Acta Biol. Acad. Sci. Hung. 32, 301–310 (1982).

1981 (1)

A. Fahr, P. Lauger, E. Bamberg, “Photocurrent Kinetics of Purple-Membrane Sheets Bound to Planar Bilayer Membranes,” J. Membrane Biol. 60, 51–62 (1981).
[Crossref]

1978 (1)

O. Kalisky, U. Lachish, M. Ottolenghi, “Time Resolution of a Back Photoreaction in Bacteriorhodopsin,” Photochem. Photobiol. 28, 261–263 (1978).
[Crossref]

1977 (1)

B. Becher, T. G. Ebrey, “The Quantum Efficiency for the Photochemical Conversion of the Purple Membrane Protein,” Biophys. J. 17, 185–191 (1977).
[Crossref] [PubMed]

1974 (1)

D. Oesterhelt, W. Stoeckenius, “Isolation of the Cell Membrane of Halobacterium halobium and its Fractionation in the Red and Purple Membrane,” Methods Enzymol. 31, 667–678 (1974).
[Crossref] [PubMed]

Bamberg, E.

A. Fahr, P. Lauger, E. Bamberg, “Photocurrent Kinetics of Purple-Membrane Sheets Bound to Planar Bilayer Membranes,” J. Membrane Biol. 60, 51–62 (1981).
[Crossref]

Becher, B.

B. Becher, T. G. Ebrey, “The Quantum Efficiency for the Photochemical Conversion of the Purple Membrane Protein,” Biophys. J. 17, 185–191 (1977).
[Crossref] [PubMed]

Chen, Z.

H. Takei, A. Lewis, Z. Chen, I. Nebenzahl, “Implementing receptive fields with excitatory and inhibitory optoelectrical responses of bacteriorhodopsin films,” Applied Optics, 30, 500–509 (1991).
[Crossref] [PubMed]

Z. Chen, A. Lewis, H. Takei, I. Nebenzahl, “BR Oriented in Polyvinylalcohol Films as an Erasable Optical Storage Medium,” submitted for publication.

Ebrey, T. G.

B. Becher, T. G. Ebrey, “The Quantum Efficiency for the Photochemical Conversion of the Purple Membrane Protein,” Biophys. J. 17, 185–191 (1977).
[Crossref] [PubMed]

Fahr, A.

A. Fahr, P. Lauger, E. Bamberg, “Photocurrent Kinetics of Purple-Membrane Sheets Bound to Planar Bilayer Membranes,” J. Membrane Biol. 60, 51–62 (1981).
[Crossref]

Franz, M. A.

H. J. Polland, M. A. Franz, W. Zenith, W. Kaiser, E. Kolling, D. Oersterhelt, “Femtosecond Photochemistry of Bacteriorhodopsin,” Biophys. J. 49, 651–662 (1986); ;R. A. Mathies, C. H. Brito Cruz, W. T. Pollard, C. V. Shank, “Direct Observation of the Femtosecond Excited-State cis-trans Isomerization in Bacteriorhodopsin,” Science 240, 777–779 (1988).
[Crossref] [PubMed]

Groma, G. I.

G. I. Groma, G. Szabo, G. Varo, “Direct Measurement of Picosecond Charge Separation in Bacteriorhodopsin,” Nature London 308, 577–558 (1984).
[Crossref]

Ippen, E.

E. Ippen, C. V. Shank, A. Lewis, M. Marcus, “Subpicosecond Spectroscopy of Bacteriorhodopsin,” Science200, 1279–1281 (1978); ;M. C. Downer, M. Islam, C. V. Shank, A. Harootunian, A. Lewis, “Title,” in Ultrafast Phonomena IV, D. H. Austin, K. B. Eisenthal, Eds. (Springer-Verlag, Berling, 1984).
[Crossref]

Ivanitsky, G. R.

N. N. Vsebolodov, G. R. Ivanitsky, “Biological Photosensory Complexes as Technical Information Carriers,” Biofizika 30, 884–887 (1985).

Kaiser, W.

H. J. Polland, M. A. Franz, W. Zenith, W. Kaiser, E. Kolling, D. Oersterhelt, “Femtosecond Photochemistry of Bacteriorhodopsin,” Biophys. J. 49, 651–662 (1986); ;R. A. Mathies, C. H. Brito Cruz, W. T. Pollard, C. V. Shank, “Direct Observation of the Femtosecond Excited-State cis-trans Isomerization in Bacteriorhodopsin,” Science 240, 777–779 (1988).
[Crossref] [PubMed]

Kalisky, O.

O. Kalisky, U. Lachish, M. Ottolenghi, “Time Resolution of a Back Photoreaction in Bacteriorhodopsin,” Photochem. Photobiol. 28, 261–263 (1978).
[Crossref]

Kolling, E.

H. J. Polland, M. A. Franz, W. Zenith, W. Kaiser, E. Kolling, D. Oersterhelt, “Femtosecond Photochemistry of Bacteriorhodopsin,” Biophys. J. 49, 651–662 (1986); ;R. A. Mathies, C. H. Brito Cruz, W. T. Pollard, C. V. Shank, “Direct Observation of the Femtosecond Excited-State cis-trans Isomerization in Bacteriorhodopsin,” Science 240, 777–779 (1988).
[Crossref] [PubMed]

Lachish, U.

O. Kalisky, U. Lachish, M. Ottolenghi, “Time Resolution of a Back Photoreaction in Bacteriorhodopsin,” Photochem. Photobiol. 28, 261–263 (1978).
[Crossref]

Lauger, P.

A. Fahr, P. Lauger, E. Bamberg, “Photocurrent Kinetics of Purple-Membrane Sheets Bound to Planar Bilayer Membranes,” J. Membrane Biol. 60, 51–62 (1981).
[Crossref]

Lewis, A.

H. Takei, A. Lewis, Z. Chen, I. Nebenzahl, “Implementing receptive fields with excitatory and inhibitory optoelectrical responses of bacteriorhodopsin films,” Applied Optics, 30, 500–509 (1991).
[Crossref] [PubMed]

Z. Chen, A. Lewis, H. Takei, I. Nebenzahl, “BR Oriented in Polyvinylalcohol Films as an Erasable Optical Storage Medium,” submitted for publication.

E. Ippen, C. V. Shank, A. Lewis, M. Marcus, “Subpicosecond Spectroscopy of Bacteriorhodopsin,” Science200, 1279–1281 (1978); ;M. C. Downer, M. Islam, C. V. Shank, A. Harootunian, A. Lewis, “Title,” in Ultrafast Phonomena IV, D. H. Austin, K. B. Eisenthal, Eds. (Springer-Verlag, Berling, 1984).
[Crossref]

Marcus, M.

E. Ippen, C. V. Shank, A. Lewis, M. Marcus, “Subpicosecond Spectroscopy of Bacteriorhodopsin,” Science200, 1279–1281 (1978); ;M. C. Downer, M. Islam, C. V. Shank, A. Harootunian, A. Lewis, “Title,” in Ultrafast Phonomena IV, D. H. Austin, K. B. Eisenthal, Eds. (Springer-Verlag, Berling, 1984).
[Crossref]

Nebenzahl, I.

H. Takei, A. Lewis, Z. Chen, I. Nebenzahl, “Implementing receptive fields with excitatory and inhibitory optoelectrical responses of bacteriorhodopsin films,” Applied Optics, 30, 500–509 (1991).
[Crossref] [PubMed]

Z. Chen, A. Lewis, H. Takei, I. Nebenzahl, “BR Oriented in Polyvinylalcohol Films as an Erasable Optical Storage Medium,” submitted for publication.

Oersterhelt, D.

H. J. Polland, M. A. Franz, W. Zenith, W. Kaiser, E. Kolling, D. Oersterhelt, “Femtosecond Photochemistry of Bacteriorhodopsin,” Biophys. J. 49, 651–662 (1986); ;R. A. Mathies, C. H. Brito Cruz, W. T. Pollard, C. V. Shank, “Direct Observation of the Femtosecond Excited-State cis-trans Isomerization in Bacteriorhodopsin,” Science 240, 777–779 (1988).
[Crossref] [PubMed]

Oesterhelt, D.

D. Oesterhelt, W. Stoeckenius, “Isolation of the Cell Membrane of Halobacterium halobium and its Fractionation in the Red and Purple Membrane,” Methods Enzymol. 31, 667–678 (1974).
[Crossref] [PubMed]

Ottolenghi, M.

O. Kalisky, U. Lachish, M. Ottolenghi, “Time Resolution of a Back Photoreaction in Bacteriorhodopsin,” Photochem. Photobiol. 28, 261–263 (1978).
[Crossref]

Polland, H. J.

H. J. Polland, M. A. Franz, W. Zenith, W. Kaiser, E. Kolling, D. Oersterhelt, “Femtosecond Photochemistry of Bacteriorhodopsin,” Biophys. J. 49, 651–662 (1986); ;R. A. Mathies, C. H. Brito Cruz, W. T. Pollard, C. V. Shank, “Direct Observation of the Femtosecond Excited-State cis-trans Isomerization in Bacteriorhodopsin,” Science 240, 777–779 (1988).
[Crossref] [PubMed]

Poltoratski, V. A.

N. N. Vsevolodov, V. A. Poltoratski, “Holograms in Biochrome, a Biological Photochromic Material,” Sov. Phys. Tech. Phys. 30, 1235 (1985).

Shank, C. V.

E. Ippen, C. V. Shank, A. Lewis, M. Marcus, “Subpicosecond Spectroscopy of Bacteriorhodopsin,” Science200, 1279–1281 (1978); ;M. C. Downer, M. Islam, C. V. Shank, A. Harootunian, A. Lewis, “Title,” in Ultrafast Phonomena IV, D. H. Austin, K. B. Eisenthal, Eds. (Springer-Verlag, Berling, 1984).
[Crossref]

Stoeckenius, W.

D. Oesterhelt, W. Stoeckenius, “Isolation of the Cell Membrane of Halobacterium halobium and its Fractionation in the Red and Purple Membrane,” Methods Enzymol. 31, 667–678 (1974).
[Crossref] [PubMed]

Szabo, G.

G. I. Groma, G. Szabo, G. Varo, “Direct Measurement of Picosecond Charge Separation in Bacteriorhodopsin,” Nature London 308, 577–558 (1984).
[Crossref]

Takei, H.

H. Takei, A. Lewis, Z. Chen, I. Nebenzahl, “Implementing receptive fields with excitatory and inhibitory optoelectrical responses of bacteriorhodopsin films,” Applied Optics, 30, 500–509 (1991).
[Crossref] [PubMed]

Z. Chen, A. Lewis, H. Takei, I. Nebenzahl, “BR Oriented in Polyvinylalcohol Films as an Erasable Optical Storage Medium,” submitted for publication.

Varo, G.

G. I. Groma, G. Szabo, G. Varo, “Direct Measurement of Picosecond Charge Separation in Bacteriorhodopsin,” Nature London 308, 577–558 (1984).
[Crossref]

G. Varo, “Dried Oriented Purple Membrane Samples,” Acta Biol. Acad. Sci. Hung. 32, 301–310 (1982).

Vsebolodov, N. N.

N. N. Vsebolodov, G. R. Ivanitsky, “Biological Photosensory Complexes as Technical Information Carriers,” Biofizika 30, 884–887 (1985).

Vsevolodov, N. N.

N. N. Vsevolodov, V. A. Poltoratski, “Holograms in Biochrome, a Biological Photochromic Material,” Sov. Phys. Tech. Phys. 30, 1235 (1985).

Zenith, W.

H. J. Polland, M. A. Franz, W. Zenith, W. Kaiser, E. Kolling, D. Oersterhelt, “Femtosecond Photochemistry of Bacteriorhodopsin,” Biophys. J. 49, 651–662 (1986); ;R. A. Mathies, C. H. Brito Cruz, W. T. Pollard, C. V. Shank, “Direct Observation of the Femtosecond Excited-State cis-trans Isomerization in Bacteriorhodopsin,” Science 240, 777–779 (1988).
[Crossref] [PubMed]

Acta Biol. Acad. Sci. Hung. (1)

G. Varo, “Dried Oriented Purple Membrane Samples,” Acta Biol. Acad. Sci. Hung. 32, 301–310 (1982).

Applied Optics (1)

H. Takei, A. Lewis, Z. Chen, I. Nebenzahl, “Implementing receptive fields with excitatory and inhibitory optoelectrical responses of bacteriorhodopsin films,” Applied Optics, 30, 500–509 (1991).
[Crossref] [PubMed]

Biofizika (1)

N. N. Vsebolodov, G. R. Ivanitsky, “Biological Photosensory Complexes as Technical Information Carriers,” Biofizika 30, 884–887 (1985).

Biophys. J. (2)

H. J. Polland, M. A. Franz, W. Zenith, W. Kaiser, E. Kolling, D. Oersterhelt, “Femtosecond Photochemistry of Bacteriorhodopsin,” Biophys. J. 49, 651–662 (1986); ;R. A. Mathies, C. H. Brito Cruz, W. T. Pollard, C. V. Shank, “Direct Observation of the Femtosecond Excited-State cis-trans Isomerization in Bacteriorhodopsin,” Science 240, 777–779 (1988).
[Crossref] [PubMed]

B. Becher, T. G. Ebrey, “The Quantum Efficiency for the Photochemical Conversion of the Purple Membrane Protein,” Biophys. J. 17, 185–191 (1977).
[Crossref] [PubMed]

J. Membrane Biol. (1)

A. Fahr, P. Lauger, E. Bamberg, “Photocurrent Kinetics of Purple-Membrane Sheets Bound to Planar Bilayer Membranes,” J. Membrane Biol. 60, 51–62 (1981).
[Crossref]

Methods Enzymol. (1)

D. Oesterhelt, W. Stoeckenius, “Isolation of the Cell Membrane of Halobacterium halobium and its Fractionation in the Red and Purple Membrane,” Methods Enzymol. 31, 667–678 (1974).
[Crossref] [PubMed]

Nature London (1)

G. I. Groma, G. Szabo, G. Varo, “Direct Measurement of Picosecond Charge Separation in Bacteriorhodopsin,” Nature London 308, 577–558 (1984).
[Crossref]

Photochem. Photobiol. (1)

O. Kalisky, U. Lachish, M. Ottolenghi, “Time Resolution of a Back Photoreaction in Bacteriorhodopsin,” Photochem. Photobiol. 28, 261–263 (1978).
[Crossref]

Sov. Phys. Tech. Phys. (1)

N. N. Vsevolodov, V. A. Poltoratski, “Holograms in Biochrome, a Biological Photochromic Material,” Sov. Phys. Tech. Phys. 30, 1235 (1985).

Other (3)

L. P. Packer, Ed., Methods in Enzymology, Vol. 88 (Academic, New York, 1982).

E. Ippen, C. V. Shank, A. Lewis, M. Marcus, “Subpicosecond Spectroscopy of Bacteriorhodopsin,” Science200, 1279–1281 (1978); ;M. C. Downer, M. Islam, C. V. Shank, A. Harootunian, A. Lewis, “Title,” in Ultrafast Phonomena IV, D. H. Austin, K. B. Eisenthal, Eds. (Springer-Verlag, Berling, 1984).
[Crossref]

Z. Chen, A. Lewis, H. Takei, I. Nebenzahl, “BR Oriented in Polyvinylalcohol Films as an Erasable Optical Storage Medium,” submitted for publication.

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Figures (16)

Fig. 1
Fig. 1

Bacteriorhodopsin photocycle with respect to the inner and outer membrane surfaces of the purple membrane (respectively, the side of the membrane in the bacterium that points to the inside of the cell and the side which faces the solution). In the photocycle shown, solid thick-lined arrows represent the thermal decay of a species, and dashed arrows represent photochemical processes. The bacteriorhodopsin molecule is embedded vectorially in the purple membrane, and as a function of the transformation induced by light it ejects a proton to the outer side in the bR to M transformation and takes up a proton in the M to bR in the regeneration process. In wet membranes protons are pumped from the inside (the p1 pathway shown as a thin lined arrow) to the outside. However, in the experiments reported in this paper on dried membranes with borate buffer, the proton uptake pathway is represented by p2 in the figure. This results in electrical properties with a reverse polarity in the reactions that regenerate bR in dried membranes.

Fig. 2
Fig. 2

Three different images impressed on the same film of dried bR. These images were photographed ~10 s after they were impressed on the bR. The photography required four light sources which themselves bleached the film and reduced the contrast in the images. The thickness of the lines used to produce the letters is ~0.1 mm. The purple membrane/bR medium is expected to be an ultrahigh resolution film since the photochemical reaction producing the image is ultimately determined by photon absorption in a single bR molecule. The dark regions in these images are the purple bR molecules and the light regions are the yellow M molecules.

Fig. 3
Fig. 3

(A) The bR/M and M/bR photocurrent measured so that the bR–M transition involves movement of charge toward the glass electrode, and the M–bR transition is associated with a charge movement toward an opposite polarity platinum electrode. (B) The same as in (A) with cooling.

Fig. 4
Fig. 4

Four-synapse matrix to simulate the ultimate neural network architecture envisioned in this paper.

Fig. 5
Fig. 5

Experimental system.

Fig. 6
Fig. 6

Writing and reading the photocurrent generated by a four synapse network. The photocurrent records show the input currents to the two neurons. When in (A) both synapses are transferred to the M state in the writing step, (B) one synapse leading to neuron 1 is transferred to M, (C) two synapses, one leading to neuron 1 and the other to neuron 2 are in M, (D) three synapses, one leading to neuron 1 & the other two leading to neuron 2 are in M.

Fig. 7
Fig. 7

Open (A) and closed (B) loop photocurrents for a single synapse.

Fig. 8
Fig. 8

(a) Schematic of bR photocurrent experiments with diodes in series with opposite connections. (b) Results from experiments that measured the photocurrent with diodes in the two opposite connections shown in (a). Peak A corresponds to connection A, and peak B corresponds to connection B.

Fig. 9
Fig. 9

Bacteriorhodopsin neural network: Each synapse is composed of oriented bR with borate buffer to stabilize M. The synapses produce a photocurrent during the reading step with amplitudes that depend on the writing step.

Fig. 10
Fig. 10

Neural network truth table in which Tij is the synaptic strength, and Ni is the state of the neuron. When the neuron is in state 1, the current is 1 × Tij, and when the neuron is 0 the current is 0.

Fig. 11
Fig. 11

(A) Output connections from neuron Ni; (B) input connections to neuron Ni.

Fig. 12
Fig. 12

Electrical scheme for a four-synapse matrix in which each synapse is connected in parallel to FJT1100 diodes.

Fig. 13
Fig. 13

Photocurrent results with a four-synapse matrix where each synapse is connected in parallel to FJT1100 diodes.

Fig. 14
Fig. 14

Steps in the read without erase procedure: (A) the initial state where all the molecules are in the bR state; (B) the writing step where some molecules are converted with light to state M; (C) the reading step where a fraction of the remaining molecules in the bR state are photochemically exchanged between bR and K. The magnitude of the photocurrent developed during the reading step depends on the amount of molecules that were transferred to the M state during the writing step. Thus this process of read without erase produces a reprogammable pulse of photocurrent D. The arrangement of light sources employed for the read without erase experiments.

Fig. 15
Fig. 15

Photocurrent response of a bR pixel excited by a 350-ns, 570-nm pulse in which (A) all the molecules are in the bR state and (B) all the molecules are in the M state.

Fig. 16
Fig. 16

Read without erase experiment. Each 20-μs time interval corresponds to the photocurrent response of a bR pixel excited by two time delayed pulses in the red R and yellow Y region of the spectrum. In each set of pulses the time delay was varied. In the third 20-μs time interval the read without erase effect is shown. In this experiment all the K molecules are transferred back to the bR state by the red pulse.

Tables (1)

Tables Icon

Table I Expected Photocurrent from Two Neurons for Synapses in the bR State with Various Combinations of Switches that Produce Closed and Open Loops In the bR Neural Network Architecture

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