US5663571A
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Quantum memory
Assignee: Sony Corp
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Filing: 1995-04-18
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Granted: 1997-09-02
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Expires: 2015-04-18
Abstract
Abstract A quantum memory has memory cells, each of the memory cells includes three-stage quantum dots stacked in sequence. A memory cell array is constructed by two-dimensionally arranging the memory cells. The quantum dots are made of heterojunctions of compound semiconductors. Writing and reading to and from a memory cell are executed by bringing a needle electrode close to the memory cell to apply an external electric field while irradiating laser light to an area including the memory cell.
Inventors
- 👤 Ryuichi Ugajin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:53
CPC Classifications
H; H10; H10F; H10F77/00; H10F77/10; H10F77/14; B; B82; B82Y; B82Y10/00
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
221 words
A quantum memory, comprising: a plurality of memory cells; each of said memory cells comprising a first quantum box, a second quantum box and a third quantum box which are stacked in sequence; and said first quantum box and said second quantum box being coupled by a coupling strength different from a coupling strength between said second quantum box and said third quantum box, and further satisfying the relationship: E 0 .sup.(j-1) <E 0 .sup.(j-2) E 0 .sup.(j-3) <E 0 .sup.(j-2) (E 1 .sup.(j-1) -E 0 .sup.(j-1))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 1 .sup.(j-3) -E 0 .sup.(j-3))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 0 .sup.(j-1) -H 0 .sup.(j-1))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) (E 0 .sup.(j-3) -H 0 .sup.(j-3))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) where E 0 .sup.(j-1), E 0 .sup.(j-2) and E 0 .sup.(j-3) are ground-state energy levels of electrons in said first quantum box, said second quantum box and said third quantum box, respectively; E 1 .sup.(j-1), E 1 .sup.(j-2) and E 1 .sup.(j-3) are first excited-state energy levels of electrons of said first quantum box, said second quantum box and said third quantum box, respectively; and H 0 .sup.(j-1), H 0 .sup.(j-2) and H 0 .sup.(j-3) are ground-state energy levels of holes in said first quantum box, said second quantum box and said third quantum box, respectively.
Claim 2
Dependent Claim
221 words
A quantum memory, comprising: a plurality of memory cells; each of said memory cells comprising a first quantum box, a second quantum box and a third quantum box which are stacked in sequence; and said first quantum box and said second quantum box being coupled by a coupling strength different from a coupling strength between said second quantum box and said third quantum box, and further satisfying the relationship: E 0 .sup.(j-1) <E 0 .sup.(j-2) E 0 .sup.(j-3) <E 0 .sup.(j-2) (E 1 .sup.(j-1) -E 0 .sup.(j-1))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 1 .sup.(j-3) -E 0 .sup.(j-3))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 0 .sup.(j-1) -H 0 .sup.(j-1))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) (E 0 .sup.(j-3) -H 0 .sup.(j-3))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) where E 0 .sup.(j-1), E 0 .sup.(j-2) and E 0 .sup.(j-3) are ground-state energy levels of electrons in said first quantum box, said second quantum box and said third quantum box, respectively; E 1 .sup.(j-1), E 1 .sup.(j-2) and E 1 .sup.(j-3) are first excited-state energy levels of electrons of said first quantum box, said second quantum box and said third quantum box, respectively; and H 0 .sup.(j-1), H 0 .sup.(j-2) and H 0 .sup.(j-3) are ground-state energy levels of holes in said first quantum box, said second quantum box and said third quantum box, respectively.
Claim 3
Dependent Claim
82 words
The quantum memory according to claim 1 wherein, during writing, a first external electric field in the stacking direction of said first, second and third quantum boxes is applied to a memory cell chosen for writing while irradiating first light to said memory cell, and wherein, during reading, a second external electric field in the opposite direction from that of said first external electric field is applied to a memory cell chosen for reading while irradiating second light to said memory cell.
Claim 4
Dependent Claim
33 words
The quantum memory according to claim 2 wherein said first external electric field is applied by bringing a needle electrode applied with a predetermined voltage close to said memory cell chosen for writing.
Claim 5
Dependent Claim
44 words
The quantum memory according to claim 2 wherein initialization of a memory cell chosen for initialization is done by applying to said memory cell a third external electric field larger than said second external electric field to cause electron-hole recombination in said memory cell.
Claim 6
Dependent Claim
33 words
The quantum memory according to claim 1, wherein initialization of all said memory cells is done by increasing the temperature of said quantum memory to cause electron-hole recombination in all said memory cells.
Claim 7
Dependent Claim
28 words
The quantum memory according to claim 1 wherein said first quantum box, said second quantum box and said third quantum box are made of heterojunctions of compound semiconductors.
Claim 8
Dependent Claim
17 words
The quantum memory according to claim 6 wherein said heterojunctions of compound semiconductors are type-I heterojunction superlattices.
Claim 9
Dependent Claim
22 words
The quantum memory according to claim 6 wherein said heterojunctions of compound semiconductors includes heterojunctions selected from AlGaAs/GaAs heterojunctions or AlGaAs/InGaAs heterojunctions.
Claim 10
Dependent Claim
17 words
The quantum memory according to claim 6 wherein said heterojunctions of compound semiconductors are type-II heterojunction superlattices.
Claim 11
Dependent Claim
24 words
The quantum memory according to claim 6 wherein said heterojunctions of compound semiconductors include heterojunctions selected from AlSb/InAs heterojunctions, GaSb/InAs heterojunctions or AlSb/GaSb heterojunctions.
Claim 12
Dependent Claim
251 words
A quantum memory, comprising: a plurality of memory cells; each of said memory cells comprising a first quantum box, a second quantum box and a third quantum box which are stacked in sequence; and said first quantum box and said second quantum box being coupled by a coupling strength wherein said coupling strength between said second quantum box and said third quantum box is larger than said coupling strength between said first quantum box and said second quantum box and further satisfying the relationships: E 0 .sup.(j-1) <E 0 .sup.(j-2) E 0 .sup.(j-3) <E 0 .sup.(j-2) (E 1 .sup.(j-1) -E 0 .sup.(j-1))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 1 .sup.(j-3) -E 0 .sup.(j-3))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 0 .sup.(j-1) -H 0 .sup.(j-1))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) (E 0 .sup.(j-3) -H 0 .sup.(j-3))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) where E 0 .sup.(j-1), E 0 .sup.(j-2) and E 0 .sup.(j-3) are ground-state energy levels of electrons in said first quantum box, said second quantum box and said third quantum box, respectively; E 1 .sup.(j-1), E 1 .sup.(j-2) and E 1 .sup.(j-3) are first excited-state energy levels of electrons of said first quantum box, said second quantum box and said third quantum box, respectively; H 0 .sup.(j-1), H 0 .sup.(j-2) and H 0 .sup.(j-3) are ground-state energy levels of holes in said first quantum box, said second quantum box and said third quantum box, respectively; and wherein said first, second and third quantum boxes are made of heterojunctions of compound semiconductors.
Claim 13
Dependent Claim
251 words
A quantum memory, comprising: a plurality of memory cells; each of said memory cells comprising a first quantum box, a second quantum box and a third quantum box which are stacked in sequence; and said first quantum box and said second quantum box being coupled by a coupling strength wherein said coupling strength between said second quantum box and said third quantum box is larger than said coupling strength between said first quantum box and said second quantum box and further satisfying the relationships: E 0 .sup.(j-1) <E 0 .sup.(j-2) E 0 .sup.(j-3) <E 0 .sup.(j-2) (E 1 .sup.(j-1) -E 0 .sup.(j-1))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 1 .sup.(j-3) -E 0 .sup.(j-3))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 0 .sup.(j-1) -H 0 .sup.(j-1))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) (E 0 .sup.(j-3) -H 0 .sup.(j-3))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) where E 0 .sup.(j-1), E 0 .sup.(j-2) and E 0 .sup.(j-3) are ground-state energy levels of electrons in said first quantum box, said second quantum box and said third quantum box, respectively; E 1 .sup.(j-1), E 1 .sup.(j-2) and E 1 .sup.(j-3) are first excited-state energy levels of electrons of said first quantum box, said second quantum box and said third quantum box, respectively; H 0 .sup.(j-1), H 0 .sup.(j-2) and H 0 .sup.(j-3) are ground-state energy levels of holes in said first quantum box, said second quantum box and said third quantum box, respectively; and wherein said first, second and third quantum boxes are made of heterojunctions of compound semiconductors.
Claim 14
Independent Claim
308 words
A method of writing to a quantum memory cell, comprising the steps of: providing a quantum memory cell comprising a first, second and third quantum box stacked in sequence each of said memory cells comprising a first quantum box, a second quantum box and a third quantum box which are stacked in sequence; and said first quantum box and said second quantum box being coupled by a coupling strength wherein said coupling strength between said second quantum box and said third quantum box is larger than said coupling strength between said first quantum box and said second quantum box and further satisfying the relationships: E 0 .sup.(j-1) <E 0 .sup.(j-2) E 0 .sup.(j-3) <E 0 .sup.(j-2) (E 1 .sup.(j-1) -E 0 .sup.(j-1))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 1 .sup.(j-3) -E 0 .sup.(j-3))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 0 .sup.(j-1) -H 0 .sup.(j-1))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) (E 0 .sup.(j-3) -H 0 .sup.(j-3))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) where E 0 .sup.(j-1), E 0 .sup.(j-2) and E 0 .sup.(j-3) are ground-state energy levels of electrons in said first quantum box, said second quantum box and said third quantum box, respectively; E 1 .sup.(j-1), E 1 .sup.(j-2) and E 1 .sup.(j-3) are first excited-state energy levels of electrons of said first quantum box, said second quantum box and said third quantum box, respectively; H 0 .sup.(j-1), H 0 .sup.(j-2) and H 0 .sup.(j-3) are ground-state energy levels of holes in said first quantum box, said second quantum box and said third quantum box, respectively; and wherein said first, second and third quantum boxes are made of heterojunctions of compound semiconductors; applying a first electric field of a first polarity to said quantum memory cell in the stacking direction of said first, second and third quantum boxes; simultaneous with said applying step, irradiating said memory cell with light.
Claim 15
Independent Claim
308 words
A method of writing to a quantum memory cell, comprising the steps of: providing a quantum memory cell comprising a first, second and third quantum box stacked in sequence each of said memory cells comprising a first quantum box, a second quantum box and a third quantum box which are stacked in sequence; and said first quantum box and said second quantum box being coupled by a coupling strength wherein said coupling strength between said second quantum box and said third quantum box is larger than said coupling strength between said first quantum box and said second quantum box and further satisfying the relationships: E 0 .sup.(j-1) <E 0 .sup.(j-2) E 0 .sup.(j-3) <E 0 .sup.(j-2) (E 1 .sup.(j-1) -E 0 .sup.(j-1))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 1 .sup.(j-3) -E 0 .sup.(j-3))>(E 1 .sup.(j-2) -E 0 .sup.(j-2)) (E 0 .sup.(j-1) -H 0 .sup.(j-1))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) (E 0 .sup.(j-3) -H 0 .sup.(j-3))≠(E 0 .sup.(j-2) -H 0 .sup.(j-2)) where E 0 .sup.(j-1), E 0 .sup.(j-2) and E 0 .sup.(j-3) are ground-state energy levels of electrons in said first quantum box, said second quantum box and said third quantum box, respectively; E 1 .sup.(j-1), E 1 .sup.(j-2) and E 1 .sup.(j-3) are first excited-state energy levels of electrons of said first quantum box, said second quantum box and said third quantum box, respectively; H 0 .sup.(j-1), H 0 .sup.(j-2) and H 0 .sup.(j-3) are ground-state energy levels of holes in said first quantum box, said second quantum box and said third quantum box, respectively; and wherein said first, second and third quantum boxes are made of heterojunctions of compound semiconductors; applying a first electric field of a first polarity to said quantum memory cell in the stacking direction of said first, second and third quantum boxes; simultaneous with said applying step, irradiating said memory cell with light.
Claim 16
Dependent Claim
36 words
The method of claim 12, further comprising reading said memory cell by the steps of applying a second electric field having polarity opposite that of said first polarity while simultaneously irradiating said memory cell with light.
Claim 17
Dependent Claim
32 words
The method of claim 12, wherein said step of applying said first electric field includes the step of bringing a needle electrode at a first predetermined voltage close to said memory cell.
Claim 18
Dependent Claim
32 words
The method of claim 12, wherein said step of applying said second electric field includes the step of bringing a needle electrode at a second predetermined voltage close to said memory cell.
Claim 19
Dependent Claim
37 words
The method of claim 13, further comprising initializing said memory cell by the step of applying a third electric field to said memory cell, said third electric field being of greater strength than said second electric field.
Claim 20
Dependent Claim
45 words
The method of claim 13, further comprising initializing said memory cell by the step of applying said second electric field to said memory cell for a time longer than that for reading said memory cell in order to cause electron-hole recombination in said memory cell.
Claim 21
Dependent Claim
27 words
The method of claim 12, further comprising initializing said memory cell by the step of increasing the temperature of said quantum memory cell to cause electron-hole recombination.
Claim 22
Dependent Claim
32 words
The method of claim 12, wherein said providing step includes the step of forming said first quantum box, said second quantum box and said third quantum box of heterojunctions of compound semiconductors.
Claim 23
Dependent Claim
15 words
The method of claim 19, wherein said heterojunctions of compound semiconductors include type-I heterojunction superlattices.
Claim 24
Dependent Claim
20 words
The method of claim 20, wherein said heterojunctions of compound semiconductors include heterojunctions selected from AlGaAs/GaAs heterojunctions or AlGaAs/InGaAs heterojunctions.
Claim 25
Dependent Claim
15 words
The method of claim 19, wherein said heterojunctions of compound semiconductors include type-II heterojunction superlattices.
Claim 26
Dependent Claim
22 words
The method of claim 22, wherein said heterojunctions of compound semiconductors include heterojunctions selected from AlSb/InAs heterojunctions, GaSb/InAs heterojunctions and AlSb/GaSb heterojunctions.
Claim 27
Dependent Claim
33 words
The quantum memory according to claim 2 wherein said second external electric field is applied by bringing a needle electrode applied with a predetermined voltage close to said memory cell chosen for reading.
Claim 28
Dependent Claim
47 words
The quantum memory according to claim 2 wherein initialization of a memory cell chosen for initialization is done by applying to said memory cell said second external electric field for a time longer than that for reading in order to cause electron-hole recombination in said memory cell.
Claim 29
Dependent Claim
33 words
The quantum memory according to claim 1, wherein initialization of all said memory cells is done by irradiating third light to said quantum memory to cause electron-hole recombination in all said memory cells.
References Cited (Backward Citations)
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