ENTANGLEMENT OF EXCITONS BY ACOUSTIC GUIDING

Abstract

A system is described that exhibits the functionality of a beam-splitter, typically an optical device that splits a beam of light in two. In this case, the beams are acoustic pulses and can lead to the creation of a Wannier-Mott exciton: a bound state of an electron and an electron hole whose attraction to each other is maintained by the electrostatic Coulomb force. This exciton beam-splitter is lossy (i.e., involves the dissipation of electrical or electromagnetic energy). Half of the time the exciton is radiated away. Nevertheless, if the exciton is not lost, the exciton is now in a superposition of two states that can be well separated in position. Four such beam-splitters can be used to make an exciton interferometer that uses the interference patterns from the interacting acoustic pulses to extract information.

Claims

1. A method of manipulating a Wannier-Mott exciton comprising: launching a plurality of inner wave pulses of an elastic medium into one another to cause a first collision; during said first collision, raising an energy of an antisymmetric component of an exciton wave function into a continuum such that the energy is lost from a potential well produced by the elastic medium; launching a plurality of outer waves pulses toward one another to cause: second collisions between the plurality of outer waves and resulting waves from the first collision; a third collision between a subset of waves resulting from the second collisions; and a probability the Wannier-Mott exciton arrives at one or more predetermined locations based on a phase shift that can occur at a time between the second collisions and third collision; and detecting whether the Wannier-Mott exciton arrived at the one or more predetermined locations and/or collecting the Wannier-Mott exciton for quantum computation(s).

2. The method of claim 1 further comprising repeating the steps of the method until the third collision results in a merger where a symmetric exciton mode emerges with no amplitude lost.

3. The method of claim 1 further comprising controlling the phase shift and/or a distance between two wells to said probability.

4. The method of claim 1 further comprising binding the Wannier-Mott exciton with visible light to form an exciton-polariton or with sound waves to form an exciton-phonon.

5. The method of claim 1 further comprising well separating the Wannier-Mott exciton in position.

6. The method of claim 1, wherein: the elastic medium comprises an acoustic field; and the plurality of inner wave pulses and the plurality of outer wave pulses are formed from using ultrasound.

7. The method of claim 1, wherein the second collisions comprise two collisions substantially equidistantly spaced from a central location of an interferometer used to carry out the method and the first collision and the third collision occur at said central location.

8. The method of claim 1, wherein an exciton amplitude of a first inner wave pulse selected from the plurality of wave pulses is non-zero and an exciton amplitude of a second wave pulse selected from the plurality of wave pulses equals zero.

9. The method of claim 1, wherein the plurality of inner wave pulses and/or the plurality of outer wave pulses are launched from the same source and/or have a substantially similar or identical frequency.

10. The method of claim 1, further comprising extracting information from interference by measuring a physical characteristic of sound selected from the group consisting of: velocity, wavelength, absorption, impedance, and temperature.

11. A quantum computer comprising: an ultrasonic transducer capable of converting ultrasound into electrical signals and electrical signals into ultrasound; a gas or liquid through which the ultrasound can propagate; (i) a plurality of pulse splitters capable of and/or (ii) predetermined locations at which a series of collisions for: splitting and/or merging correlated or coherent acoustic pulses; and an excitonic circuit comprising at least one quantum logic gate that operates on Wannier-Mott excitons or a detection of Wannier-Mott excitons.

12. The quantum computer of claim 11, wherein the gas or liquid is kept at room temperature and still permits operation of the quantum computer.

13. The quantum computer of claim 11, further comprising qubits.

14. The quantum computer of claim 11, wherein the quantum computer is free from semiconducting materials.

15. The quantum computer of claim 11, wherein the at least one quantum logic gate operates based on exciton-phonon couplings or exciton-polaritons.

16. An exciton interferometer comprising: a source of mechanical waves; a medium possessing inertia through which the mechanical waves can propagate; a collider capable of splitting and/or merging correlated or coherent pulses; a mechanism capable of utilizing and/or binding Wannier-Mott excitons created as a result of splitting and/or merging the correlated or coherent pulses; a receiver capable of converting mechanical energy from the mechanical waves into electrical signals.

17. The exciton interferometer of claim 16, wherein the source of mechanical waves is a vibrating crystal.

18. The exciton interferometer of claim 17, further comprising a reflector placed parallel to the vibrating crystal.

19. The exciton interferometer of claim 16, wherein the mechanical waves are longitudinal waves.

20. The exciton interferometer of claim 19, wherein the correlated or coherent pulses are surface acoustic wave pulses.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Several embodiments in which the present invention can be practiced are illustrated and described in detail, wherein like reference characters represent like components throughout the several views. The drawings are presented for exemplary purposes and may not be to scale unless otherwise indicated.

[0036] FIG. 1 shows a space-time diagram of colliding acoustic pulses implementing an exciton interferometer for the case of constructive interference.

[0037] FIG. 2 shows a space-time diagram of colliding acoustic pulses implementing an exciton interferometer for the case of destructive interference.

[0038] FIGS. 3A-3C are collectively a schematic representation of excitonic quantum switches and gates that form the basis of quantum computing that include phase gates (FIG. 3A), basis-changing gate (FIG. 3B), and a controlled basis change gate (FIG. 3C). The dots represent the chromophores.

[0039] FIG. 3A is a schematic representation of a phase gate, representing a phase shifter consisting of a modified pulse splitter with two detuned nanoparticles, labeled # and *.

[0040] The phase shifter is a two-port network derived from the pulse splitter, shown in FIG. 3B, by replacing the transmission lines of ports 2 and 4 with two chromophores whose resonant frequency is slightly detuned from the rest of the chromophore circuit. The relative coupling strength between the adjacent chromophores is labeled on the corresponding link. FIG. 3B is a schematic representation of a basis-changing gate where the device nodes are labeled with the integers 1 through 4. The transmission line nodes are indicated by pairs of numbers r, m where the first labels the transmission line and the second labels a node along that transmission line. The hopping interaction coupling strengths between pairs of nodes within the device are labeled by g.sub.n, where n is 1 or 2. The hopping interaction coupling strengths between neighboring nodes along the transmission lines are all taken to be equal to g. The direction of propagation of the incoming a.sub.r.sup.in and outgoing a.sub.r.sup.out amplitudes for each of the transmission lines is also indicated.

[0041] FIG. 3C is a schematic representation of a controlled basis change gate with a phase shifting element between two basis change gates. The first basis change gate is located in shading in the upper left-hand portion of the figure. The second basis change gate is located in shading in the upper right-hand portion of the figure. The phase shifting element is located in shading in the center of the figure.

[0042] An artisan of ordinary skill in the art need not view, within isolated figure(s), the near infinite number of distinct permutations of features described in the following detailed description to facilitate an understanding of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0043] The present disclosure is not to be limited to that described herein. Mechanical, electrical, chemical, procedural, and/or other changes can be made without departing from the spirit and scope of the present invention. No features shown or described are essential to permit basic operation of the present invention unless otherwise indicated.

[0044] One-exciton states can be created by acoustic guiding. Acoustic guiding is governed by the Schrödinger equation. Here, the particular linear partial differential equation defining the wave function of a quantum-mechanical system with two colliding acoustic pulses is:

[00001]$i\hslash \frac{\partial \Psi }{\partial i}=-\frac{{\hslash }^2}{2m}\frac{{\partial }^2\Psi }{\partial x^2}+V\left(x,t\right)\Psi ,$

[0045] where V (x, t) is the potential produced by said two colliding acoustic pulses. The potential is a function of distance, x, and time, t. ψ is a wave function, ℏ is the reduced Planck constant, i is the imaginary unit, and m is the mass of the particle. The resulting acoustic potential can be modeled as:

V(x,t)=−V[δ(x−vt)+δ(x+vt)],

representing two colliding delta function potential wells, where v is the velocity of the acoustic pulse. A delta function potential supports only one bound state.

[0046] When the velocity is sufficiently slow so that the system evolves adiabatically (i.e., without transferring heat or mass between the thermodynamic system and its environment), the energy eigenstates, Eψ, can be solved for when the positions of the potential wells are held fixed. That is, one can solve the energy eigenstates of

[00002]$i\hslash \frac{\partial \Psi }{\partial i}=-\frac{{\hslash }^2}{2m}\frac{{\partial }^2\Psi }{\partial x^2}-V\delta \left(x-a\right)\Psi -V\delta \left(x+a\right)\Psi .$

V is a positive constant. 2a is the distance between the two potential wells. Writing

ψ(x,t)=ψ(x)e.sup.−iEt/ℏ,

where e is Euler's number, one obtains

[00003]$E\psi =-\frac{{\hslash }^2}{2m}\frac{{\partial }^2\psi }{\partial x^2}-V\delta \left(x-a\right)\psi -V\delta \left(x+a\right)\psi .$

[0047] when |x|≠a (x is unequal to a and unequal to −a) this equation reduces to

[00004]$E\psi =-\frac{{\hslash }^2}{2m}\frac{{\partial }^2\psi }{\partial x^2}$

writing the eigenstate ψ as:

ψ(x)=e.sup.−kx.

Substituting ψ into the immediately preceding equation yields energy, E:

[00005]$E=-\frac{{\hslash }^2{\kappa }^2}{2m}$$\mathrm{or}$${\kappa }^2=-\frac{2\mathrm{mE}}{{\hslash }^2}$

[0048] For the bound states E is negative, that is,

E=−|E|.

The wave number, κ, can then be solved for as follows:

[00006]$\kappa =\pm \sqrt{\frac{2m.Math.E.Math.}{{\hslash }^2}}.$

From this, we conclude that the wave function has the following form

[00007]$\psi \left(x\right)=\{\begin{array}{cc}{\mathrm{Ae}}^{\text{?}}& \mathrm{for}x<-a\\ {\mathrm{Be}}^{-\kappa x}+{\mathrm{Ce}}^{\kappa x}& \mathrm{for}-a<x<a\\ {\mathrm{De}}^{-\text{?}}& \mathrm{for}x>a\end{array},\text{?}\text{indicates text missing or illegible when filed}$

where κ is now taken to be positive. Because the system is symmetric under reflection, the eigenstates must be either symmetric or antisymmetric under reflection along the x axis, that is, under the transformation x.fwdarw.−x. The symmetric eigenstate, ψ.sub.S, will thus have the form

[00008]${\psi }_S\left(x\right)=\{\begin{array}{cc}{A}_S{e}^{{\kappa }_{S}x}& \mathrm{for}x<-a\\ B_S\cosh \left({\kappa }_{S}x\right)& \mathrm{for}-a<x<a\\ A_S{e}^{-{\kappa }_{S}x}& \mathrm{for}x>a\end{array}.$

The antisymmetric eigenstate, ψ.sub.A, will have the form

[00009]${\psi }_A\left(x\right)=\{\begin{array}{cc}-A_A{e}^{{\kappa }_{A}x}& \mathrm{for}x<-a\\ B_A\cosh \left({\kappa }_{A}x\right)& \mathrm{for}-a<x<a\\ A_A{e}^{-{\kappa }_{A}x}& \mathrm{for}x>a\end{array}.$

The wave function must be continuous at x=−a and x=a. This results in the conditions

A.sub.se.sup.−n.sup.S.sup.a=B.sub.s cos h(k.sub.Sα)

and

A.sub.A∈.sup.−k.sup.A.sup.a=B.sub.A sin h(k.sub.Aα)

Using these two equations to eliminate B.sub.S and B.sub.A from the equations for ψ.sub.S(x) and ψ.sub.A(x) yields:

[00010]${\psi }_S\left(x\right)=\{\begin{array}{cc}{A}_S{e}^{{\kappa }_{S}x}& \mathrm{for}x<-a\\ A_S{e}^{-{\kappa }_{S}a}\frac{\cosh \left({\kappa }_{S}x\right)}{\cosh \left({\kappa }_{S}a\right)}& \mathrm{for}-a<x<a\\ A_S{e}^{-{\kappa }_{S}x}& \mathrm{for}x>a\end{array},\mathrm{and}{\psi }_A\left(x\right)=\{\begin{array}{cc}-A_A{e}^{{\kappa }_{A}x}& \mathrm{for}x<-a\\ A_A{e}^{-{\kappa }_{A}a}\frac{\sinh \left({\kappa }_{A}x\right)}{\sinh \left({\kappa }_{A}a\right)}& \mathrm{for}-a<x<a\\ A_A{e}^{-{\kappa }_{A}x}& \mathrm{for}x>a\end{array},$

[0049] The constants A.sub.S and A.sub.A are normalization constants which can be fixed by requiring

∫.sub.−∞.sup.∞|ψ(x)|.sup.2dx=1.

Thus, imposing the conditions:

[00011]$-\frac{{\hslash }^2}{2m}\left[\frac{\partial \psi }{\partial x}{|}_{\text{?}=-a+\text{?}}-\frac{\partial \psi }{\partial x}{|}_{\text{?}=-a-\text{?}}\right]-V\psi \left(-a\right)=0$$\mathrm{and}-\frac{{\hslash }^2}{2m}\left[\frac{\partial \psi }{\partial x}{|}_{\text{?}=a+\text{?}}-\frac{\partial \psi }{\partial x}{|}_{\text{?}=a-\text{?}}\right]-V\psi \left(-a\right)=0,\text{?}\text{indicates text missing or illegible when filed}$

where one takes the limit ∈.fwdarw.0. For the symmetric eigenstate, at x=−a, one obtains from the equations above:

[00012]$\frac{\partial {\psi }_S}{\partial x}{|}_{\text{?}=-a+\text{?}}=-{\kappa }_S{A}_S{e}^{-{\kappa }_{S}a}\tanh \left({\text{?}}_{S}a\right),\frac{\partial {\psi }_S}{\partial x}{|}_{\text{?}=-a-\text{?}}={\kappa }_S{A}_S{e}^{-{\kappa }_{S}a}$$\mathrm{and}$${\psi }_S\left(-a\right)=A_S{e}^{-{\kappa }_{S}a}.\text{?}\text{indicates text missing or illegible when filed}$

[0050] Substituting these last three equations into the imposed conditions yields:

[00013]$\frac{{\hslash }^2{\kappa }_S}{2m}\left[\tanh \left({\kappa }_{S}a\right)+1\right]=V.$

which further yields

[00014]$\frac{{\kappa }_S{e}^{{\kappa }_{S}a}}{\cosh \left({\kappa }_{S}a\right)}=\frac{2\mathrm{mV}}{{\hslash }^2}.$

[0051] The left-hand side of this equation is a monotonically increasing function of KA ranging from 0 to ∞ as K.sub.A ranges from 0 to ∞. Hence, it is evident that the preceding equation always has a solution for K.sub.S and this solution is unique. In other words, there is only one symmetric energy eigenstate. Given K.sub.S, the energy eigenvalue E can then be computed as described above. Note that at a=0, the distance at which the two potential wells coincide, the preceding equation is still well behaved.

[0052] For the antisymmetric eigenstate, at x=−a one obtains for ψ.sub.A

[00015]$\frac{\partial {\psi }_A}{\partial x}{|}_{\text{?}=-\text{?}+\text{?}}={\kappa }_A{A}_A{e}^{-{\kappa }_A\alpha }\coth \left({\kappa }_A\alpha \right),\frac{\partial {\psi }_A}{\partial x}{|}_{x=-a-\text{?}}=-{\text{?}}_A{A}_A{e}^{-{\kappa }_{A}a}$$\mathrm{and}$${\psi }_A\left(-a\right)=-A_A{e}^{-{\text{?}}_{A}a}.\text{?}\text{indicates text missing or illegible when filed}$

[0053] Substituting these last three equations into the equation into the imposed conditions yields:

[00016]$\frac{h^2{\kappa }_A}{2m}\left[\coth \left({\kappa }_{A}a\right)+1\right]=V.$

which further yields

[00017]$\frac{{\kappa }_A{e}^{{\kappa }_{A}a}}{\sinh \left({\kappa }_{A}a\right)}=\frac{2\mathrm{mV}}{h^2}.$

and then becomes

[00018]$\frac{e^{{\kappa }_{A}a}}{a}=\frac{2\mathrm{mV}}{h^2}\mathrm{for}{\kappa }_{A}a⪡1.$

When the distance between the two potentials becomes sufficiently short, this equation will no longer have a solution. This indicates that the antisymmetric mode gets pushed into the continuum where it radiates away.

[0054] An exciton can be put into a superposition state. When

[00019]$a⪢\frac{1}{{\kappa }_S}$

and the wave functions can be approximated as

[00020]${\psi }_S=\frac{N}{\sqrt{2}}\left(e^{-\text{?}.Math.x-a.Math.}+e^{-\text{?}.Math.x+a.Math.}\right)$$\mathrm{and}$${\psi }_A=\frac{N}{\sqrt{2}}\left(e^{-\text{?}.Math.\text{?}-a.Math.}-e^{-\text{?}.Math.x+a.Math.}\right),\text{?}\text{indicates text missing or illegible when filed}$

where N is a normalization constant. Hence, a state vector with all the probability centered about x=−a is given by

[00021]${\psi }_{-a}=\frac{1}{\sqrt{2}}\left({\psi }_S-{\psi }_A\right)={\mathrm{Ne}}^{-\kappa .Math.x+a}$

[0055] This initial state is a superposition of the symmetric and the antisymmetric state. As the two potentials approach each other at a rate where the energy eigenstates evolve adiabatically, the distance is decreased, and the energy of the antisymmetric state is pushed up until it is no longer a bound state. At this point, the antisymmetric state radiates away. If the exciton has not radiated away, the exciton is now in symmetric state ψ.sub.S. As the distance between the potential wells increases the state evolves into the form from the equation where there is equal amplitude of finding the exciton in the well at x=−a and the well at x=+a. This is a one exciton entangled state.

[0056] This system exhibits the functionality of a beam-splitter. The beam-splitter is lossy in that half the time the exciton is radiated away. Nevertheless, if the exciton is not lost, it is now in a superposition of two states that can be well separated in position. Four such beam-splitters, which are collisions a, b, b′, and c, can be used to make an exciton interferometer, as shown in FIGS. 1 and 2.

[0057] The proposed interferometer scheme is shown in FIGS. 1 and 2. Initially one has four acoustic pulses propagating at time A of the figures. Only the solid black pulse 102/202 initially carries an exciton. The first collision a serves to prepare a symmetric entangled state. The second collisions b, b′ serve to direct two acoustic waves carrying equal exciton amplitude toward each other:

[00022]${\psi }_S=\frac{N}{\sqrt{2}}\left(e^{-\text{?}.Math.\text{?}-a.Math.}+e^{-\text{?}.Math.\text{?}+a.Math.}\right).\text{?}\text{indicates text missing or illegible when filed}$

[0058] An energy eigenstate has the time dependence e.sup.−iEt/h. Hence, the phase accumulated in traveling from b to c is

[00023]${\varphi }_1\simeq \frac{1}{h}{\int }_{t_{\text{?}}}^{{\text{?}}_b}\mathrm{Edt}$$\text{?}\text{indicates text missing or illegible when filed}$

Similarly, the phase accumulated in traveling from b′ to c is

[00024]${\varphi }_2\simeq \frac{1}{h}{\int }_{t_{\text{?}}}^{t_{\text{?}}^{\prime }}\mathrm{Edt}$$\text{?}\text{indicates text missing or illegible when filed}$

If the exciton energy along path b′ to c differs from that along the path to b to c, a phase difference

ϕ=ϕ.sub.2−ϕ.sub.1

is accumulated along path b′ to c. Hence, arriving at c the wave function has evolved to:

[00025]${\psi }_{\text{?}}=\frac{N}{\sqrt{2}}\left(e^{i\text{?}}{e}^{-\kappa .Math.x-a.Math.}+e^{-\kappa .Math.x+a.Math.}\right).\text{?}\text{indicates text missing or illegible when filed}$

This can be rewritten as:

[00026]${\psi }_{\text{?}}=\frac{{\mathrm{Ne}}^{i\text{?}/2}}{\sqrt{2}}\left(e^{i\text{?}/2}{e}^{-\kappa .Math.\text{?}-a.Math.}+e^{-i\text{?}/2}{e}^{-\kappa .Math.x+a.Math.}\right)$$\mathrm{or}$${\psi }_{\text{?}}=\frac{{\mathrm{Ne}}^{i\text{?}/2}}{\sqrt{2}}\left\{\cos \left(\frac{\varphi }{2}\right)\left[e^{-\kappa .Math.\text{?}-a.Math.}+e^{-i\varphi /2}{e}^{-\kappa .Math.x+a.Math.}\right]+i\sin \left(\frac{\varphi }{2}\right)\left[e^{-\kappa .Math.\text{?}-a.Math.}-e^{-i\varphi /2}{e}^{-\kappa .Math.x+a.Math.}\right]\right\}.\text{?}\text{indicates text missing or illegible when filed}$

This can be further written as

[00027]${\psi }_{\text{?}}=N_e{e}^{i\text{?}/2}\left[\cos \left(\frac{\varphi }{2}\right){\psi }_S+i\sin \left(\frac{\varphi }{2}\right){\psi }_A\right].\text{?}\text{indicates text missing or illegible when filed}$

[0059] The antisymmetric component of the amplitude is not bound to the well and escapes. Hence, the state propagating towards d and d′ is

[00028]${\psi }_{d,d^{\prime }}=N_{d,d^{\prime }}\cos \left(\frac{\varphi }{2}\right){\psi }_S$

and the probability, P, that the exciton arrives at d or d′ is

[00029]$P_{d,d^{\prime }}\propto {\cos }^2\left(\frac{\varphi }{2}\right).$

[0060] FIGS. 1 and 2 depict two cases of this, ϕ=0 and ϕ=π, respectively.

[0061] FIG. 1 shows a space-time diagram for a process of colliding acoustic pulses implemented with an exciton interferometer 100 for the case of constructive interference.

[0062] At time A, four surface acoustic wave pulses 112, 114 are launched in direction 110 from locations −z, −y, y, and z to collide with each other. The Gaussian hills 102, 104, 106, 108 are meant to represent the exciton wave function, Ψ. Solid black Gaussian hills 102 are those where the exciton amplitude is nonzero, and uncolored Gaussian hills 104 are those for which the exciton amplitude is zero (i.e., the negative of the potential well an exciton would be confined in). At time B, the two inner most acoustic pulses 112 have collided. At time C, i.e., during the collision, the energy of the antisymmetric component of the exciton wave function is raised into the continuum where it is lost from the potential well produced by the acoustic field. The amplitude remaining in the well 106 is that of the symmetric mode. Hence, as the acoustic pulses pass through each other, the exciton wave function has equal amplitude 106 in each of the emerging potential wells. At time D, second collisions b occur as the outermost pulses 114 collide with the resultant inner pulses. At time E, as with times B and C, the exciton amplitudes are further divided so that each pulse has equal exciton amplitude(s) 108, the value(s) of which is less than the value(s) of exciton amplitude(s) 106. At time F, the two innermost pulses merge at collision c. Because in FIG. 1 this is a merger of a symmetric exciton mode, no amplitude is lost in the pulse merger. At time G, a symmetric exciton mode emerges at space-time locations d, d′. The emergence results from the central pulse of the third collision c that occurred at time F. The emerging pulses have equal exciton amplitude(s) 108.

[0063] FIG. 2 shows a space-time diagram of colliding acoustic pulses implementing an exciton interferometer 200 for the case of destructive interference. The process shown using the interferometer 200 in FIG. 2 is similar to the process of using the interferometer 100 FIG. 1, with like numerals representing like elements (e.g., medium 116 is identical to medium 216). The process differs on the path from b′ to c, where the amplitude of the exciton accumulates a phase shift of π as represented by the inverted Gaussian 208n. When the two innermost pulses emerging from the second collisions b, b′ merge at c, the innermost pulses do so as an antisymmetric mode with amplitudes 208, 208π. These amplitude(s) are lost to the well during collision c, at time F. The two inner most wells remain empty and thus have zero amplitude 204 from time G onward. The phase shift π can come about by the exciton interacting with its surroundings in a way that temporarily changes its potential energy.

[0064] Excitons emerging at space-time locations d, d′ can be used directly for quantum computations and/or bound to other particles of matter and/or quasiparticles to later be used for quantum computations. For example, an exciton emerging from an acoustic guiding process of FIG. 1 can be used by an excitonic circuit in a quantum computer, see infra. The present disclosure also contemplates the exciton can first be bound to a photon or a phonon to form an exciton-polariton and an exciton-phonon coupling, respectively, see infra.

Wires, Circuits, Gates, and Quantum Computing

[0065] Quantum algorithms enable the speed-up of computation tasks such as, but not limited to, factoring and sorting. These computations may be performed by an excitonic quantum computer. The excitonic quantum computer can be made from exciton coherence wires, circuits, and gates, such as those described in co-pending, co-owned U.S. Pre-Grant Pub. No. 2019/0048036.

[0066] For example, exciton wires may be formed when a series of chromophores are held within the architecture so that when a first chromophore, the “input chromophore,” is excited and emits an exciton, the exciton passes, without loss of energy if sufficiently close, to a second chromophore. That chromophore may then pass the exciton to a third chromophore, and so on down a line of chromophores in a wave-like manner. The wires may be straight or branched and may be shaped to go in any direction within the architecture. The architecture may contain one or more wires. Depending on the architecture system used, the wires may be formed along a single nucleotide brick, such as in using the scaffold strand of nucleotide origami, or multiple bricks may comprise the wire, such as in molecular canvases.

[0067] When two or more wires are brought sufficiently close to each other such that they are nanospaced, the exciton may transfer from one wire to the other. By controlling this transfer, it is possible to build quantum circuits and gates. Two basic gates are needed for universal quantum computing: basis-change gates (FIG. 3B) and phase-shift gates (FIG. 3A). The basis-change gate functions as a signal divider in classical computer. As the exciton propagates down one wire and if another wire is sufficient close, the exciton will delocalize and enter a superposition state where it resides on both wires.

[0068] The phase-shift gate alters the exciton's phase by controlling the distance the exciton travels along the two wires. As shown in FIG. 3A, this may be done by first bringing two wires within nanospace from each other and then bending one or more wire away from the other in order to create two different lengths of the wires before bringing the wires close again.

[0069] However, with just these two types of gates, quantum computing does not outperform classical computing. A third kind of gate, the controlled basis-change gate (FIG. 3C) enables the entanglement of many-exciton states so that a network of quantum gates acts as if it is performing many different computations simultaneously. An exemplary controlled basis-change gate may be made from two basis-change gates and a phase-shift gate, with the phase-shift gate between the two basis-change gates. The controlled basis-change gate relies on the interaction between two excitons. When two excitons reside on neighboring chromophores, they feel each other's presence just like two electrons will feel each other's Coulomb repulsion when they are brought close together. The two-exciton interaction arises from static Coulomb interactions between molecules and is stronger when the molecules have an asymmetric molecular structure as compared with those with a symmetrical molecular structure. Asymmetric molecules possess a permanent electric dipole which changes sign when the molecule is excited from the ground state to the excited state. The static Coulomb interaction, in this case is a dipole-dipole interaction which, when both chromophores are excited (the two-exciton case), differs in sign from the case when only one chromophore is excited (the one-exciton case). Due to the static Coulomb interactions between chromophores, one exciton will accumulate extra phase in the presence of the other exciton. As a result, the presence or absence of one exciton can control how the other exciton moves through a basis change gate.

[0070] Additionally, additional gates may be incorporated into the architecture, such as, but not limited to, Hadamard gates, momentum switches, and Cθ gates (see Childs et al., Universal Computation by Multiparticle Quantum Walk, Science, 339, 791-94 (2013), herein incorporated by reference).

[0071] With reference to FIGS. 1 and 2, it is to be understood that controlling the distance between wells and/or controlling phase-shift gates so as only to have a finite set of phase angles can impact the probability that an exciton emerges at locations d, d′ within interferometers 100, 200. By controlling the position and optical transition energies of the various gates, a set of gates, or a quantum circuit can be achieved.

[0072] The wires, gates, and switches as discussed above can be joined together to answer questions that benefit from quantum algorithms such as, but not limited to, sorting, factoring, and database searching. To initialize the system, input chromophores could be excited using the acoustic interferometers described above with the proper wavelength of acoustic pulse in such a manner that only the desired subset of chromophores is excited when the system is hit with an initializing pulse of sound.

[0073] After initializing, the excitons then propagate from chromophore to chromophore along the wires into the various gates. The various gates then calculate the answer, such as a sorted list or mathematical problem. The output, or readout, can be done by using fluorescent reporter dyes to which the answer of the quantum computation is delivered by ordinary Förster/fluorescence resonance energy transfer (“FRET”). FRET describes energy transfer between two light-sensitive molecules. A donor chromophore, initially in its electronic excited state, may transfer energy to an acceptor chromophore through nonradiative dipole-dipole coupling. The efficiency of this energy transfer is inversely proportional to the sixth power of the distance between donor and acceptor, making FRET sensitive to small changes in distance.

[0074] Although this would be particularly beneficial for problems in which the output has a limited number of bits, these problems have applications in aeronautics, earth and space sciences, and space exploration, among other fields of research. Additionally, in these systems it has been demonstrated that quantum coherence and electronic coherence are observed at room temperature in a wet and noisy environment, which is an environment that is normally hostile to quantum coherence.

[0075] From the foregoing, it can be seen that the present invention accomplishes at least all of the stated objectives.

LIST OF REFERENCE CHARACTERS

[0076] The following table of reference characters and descriptors are not exhaustive, nor limiting, and include reasonable equivalents. If possible, elements identified by a reference character below and/or those elements which are near ubiquitous within the art can replace or supplement any element identified by another reference character.

TABLE-US-00001 TABLE 1 List of Reference Characters 100 exciton-based interferometer (constructive interference) 102 space-time location(s) of acoustic pulse with non-zero exciton amplitude (represented by 100% black Gaussian) 104 space-time location(s) of acoustic pulse with zero exciton amplitude 106 space-time location(s) of acoustic pulse with reduced exciton amplitude (represented by 50% black Gaussian) 108 space-time location(s) of acoustic pulse with further reduced exciton amplitude (represented with 25% black Gaussian) 110 direction of travel for acoustic pulses 112 inner acoustic pulse(s) 114 outer acoustic pulse(s) 116 elastic medium having inertia (e.g., liquid/gas) 200 exciton based interferometer (destructive interference) 202 space-time location(s) of acoustic pulse with non-zero exciton amplitude (represented by 100% black Gaussian) 204 space-time location(s) of acoustic pulse with zero exciton amplitude 206 space-time location(s) of acoustic pulse with reduced exciton amplitude (represented by 50% black Gaussian) 208 space-time location(s) of acoustic pulse with further reduced exciton amplitude (represented with 25% black Gaussian) 208π space-time location of acoustic pulse with phase shift 210 direction of travel for acoustic pulses 212 inner acoustic pulse(s) 214 outer acoustic pulse(s) 216 elastic medium having inertia (e.g., liquid/gas) A space-time plane when acoustic pulses are launched B space-time plane during first collision C space-time plane between first and second collisions D space-time plane during second collisions E space-time plane between second collisions and third collision F space-time plane during third collision G space-time plane subsequent to all collisions of acoustic pulses a first collision b, b′ second collisions c third collision d, d′ post collisions x central location y, −y locations of second collisions and/or launching location of inner pulses z, −z launching locations of outer pulses and/or terminating location of inner pulses π phase shift

Glossary

[0077] Unless defined otherwise, all technical and scientific terms used above have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments of the present invention pertain.

[0078] The terms “a,” “an,” and “the” include both singular and plural referents.

[0079] The term “or” is synonymous with “and/or” and means any one member or combination of members of a particular list.

[0080] The terms “invention” or “present invention” are not intended to refer to any single embodiment of the particular invention but encompass all possible embodiments as described in the specification and the claims.

[0081] The term “about” as used herein refers to slight variations in numerical quantities with respect to any quantifiable variable. Inadvertent error can occur, for example, through use of typical measuring techniques or equipment or from differences in the manufacture, source, or purity of components.

[0082] The term “substantially” refers to a great or significant extent. “Substantially” can thus refer to a plurality, majority, and/or a supermajority of said quantifiable variable, given proper context.

[0083] The term “generally” encompasses both “about” and “substantially.”

[0084] The term “configured” describes structure capable of performing a task or adopting a particular configuration. The term “configured” can be used interchangeably with other similar phrases, such as constructed, arranged, adapted, manufactured, and the like.

[0085] Terms characterizing sequential order, a position, and/or an orientation are not limiting and are only referenced according to the views presented.

[0086] As used herein, a “quantum well” is a potential well is a region of the potential energy surface from which a classical particle cannot escape if it has an energy that is less than that required to escape from that region.

[0087] The “scope” of the present invention is defined by the appended claims, along with the full scope of equivalents to which such claims are entitled. The scope of the invention is further qualified as including any possible modification to any of the aspects and/or embodiments disclosed herein which would result in other embodiments, combinations, sub-combinations, or the like that would be obvious to those skilled in the art.