US3916391A
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Josephson junction memory using vortex modes
Assignee: International Business Machines Corp
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Filing: 1974-09-12
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Granted: 1975-10-28
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Expires: 1994-09-12
Abstract
Abstract A memory array consists of Josephson junctions arranged in rows and columns of a matrix, each individual junction serving as a storage cell for one bit of information. The junction parameters are chosen such that the junctions, while remaining in their superconducting state can assume either of at least two vortex modes wherein no flux quanta or a certain number of flux quanta can be trapped within the junction. Optimum positioning of the vortex modes is achieved by appropriately shaping the junctions which has the effect of increasing the area(s) of overlap of the vortex modes. Switching between vortex modes for writing and reading of information is achieved by coincidentally applying word and bit currents to the columns and rows of the array, respectively. Switching between vortex modes generates voltage spikes which are detected by reading arrangements which are also disclosed.
Inventors
- 👤 Pierre L Gueret
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 20:27
CPC Classifications
G; G11; G11C; G11C11/00; G11C11/21; G11C11/44; Y; Y10; Y10S; Y10S505/00; Y10S505/825; Y10S505/831; Y10S505/832
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
166 words
A Josephson junction device for storing a single flux quantum in the absence of an external magnetic field comprising: first and second superconductive elements, an insulation layer the thickness of which is sufficient to permit Josephson tunneling along the length thereof disposed between said elements forming a single junction the gain characteristic, Ig vs Ic, of which has a region of overlap of at least two of its vortex modes, one of said modes, the one vortex mode, representing a binary one, and another of said modes, the zero vortex mode, representing a binary zero, means integral with at least one of said elements and said layer for changing said region of overlap such that said region contains the Ig Ic point of said gain characteristic wherein Ig is the gate current and Ic is the control current, means disposed in electrically coupled relationship with said device for storing information therein, and means disposed in electrically coupled relationship with said device for reading information stored therein.
Claim 2
Dependent Claim
166 words
A Josephson junction device for storing a single flux quantum in the absence of an external magnetic field comprising: first and second superconductive elements, an insulation layer the thickness of which is sufficient to permit Josephson tunneling along the length thereof disposed between said elements forming a single junction the gain characteristic, Ig vs Ic, of which has a region of overlap of at least two of its vortex modes, one of said modes, the one vortex mode, representing a binary one, and another of said modes, the zero vortex mode, representing a binary zero, means integral with at least one of said elements and said layer for changing said region of overlap such that said region contains the Ig Ic point of said gain characteristic wherein Ig is the gate current and Ic is the control current, means disposed in electrically coupled relationship with said device for storing information therein, and means disposed in electrically coupled relationship with said device for reading information stored therein.
Claim 3
Dependent Claim
51 words
A Josephson junction device according to claim 1 wherein said means for changing said region of overlap includes inductive means integral with at least one of said elements of value sufficient to change said region of overlap such that said region contains the Ig Ic 0 point of said gain characteristic.
Claim 4
Dependent Claim
44 words
A Josephson junction device according to claim 2 wherein said inductive means includes at least a portion of at least one of said elements being shaped to provide a narrower tunneling region between wider tunneling regions of said at least one of said elements.
Claim 5
Dependent Claim
52 words
A Josephson junction device according to claim 1 wherein said means for storing includes at least a single control element disposed in overlying relationship with said device and means coupled to said device and said control element for applying coincident gate and control currents, respectively, to said device and said control element.
Claim 6
Dependent Claim
151 words
A Josephson junction device according to claim 4 wherein said means for applying coincident gate and control currents includes sources connected to said devices and said control element, the current magnitudes and polarities of which, to write a binary one in the absence of a stored binary zero, are insufficient to change said device from a one vortex mode to a zero vortex mode, and, in the presence of a stored binary zero are sufficient to change said device from a zero vortex mode to a one vortex mode, and the current magnitudes and polarities of which, to write a binary zero in the absence of a stored binary zero, are sufficient to change said device from a one vortex mode to a zero vortex mode, and, in the presence of a stored binary zero are insufficient to change said device from a zero vortex mode to a one vortex mode.
Claim 7
Dependent Claim
53 words
A Josephson junction device according to claim 1 wherein said means for storing includes means electrically connected to said device for applying coincident currents thereto sufficient to switch said device between said vortex modes to store one binary condition and for maintaining said device in an unchanged state for another stored binary condition.
Claim 8
Dependent Claim
151 words
A Josephson junction device according to claim 6 wherein said means for applying coincident gate and control currents includes sources connected to said devices and said control element, the current magnitudes and polarities of which, to write a binary one in the absence of a stored binary zero, are insufficient to change said device from a one vortex mode to a zero vortex mode, and, in the presence of a stored binary zero are sufficient to change said device from a zero vortex mode to a one vortex mode, and the current magnitudes and polarities of which, to write a binary zero in the absence of a stored binary zero, are sufficient to change said device from a one vortex mode to a zero vortex mode, and, in the presence of a stored binary zero are insufficient to change said device from a zero vortex mode to a one vortex mode.
Claim 9
Dependent Claim
32 words
A Josephson junction device according to claim 1 further including means disposed in electromagnetically coupled relationship with said device for compensating for the variation in maximum current density (Jmax) of said device.
Claim 10
Dependent Claim
91 words
A Josephson junction device according to claim 8 wherein said means for compensating includes first and second Josephson junctions connected in series, a control line electromagnetically coupled to said device connected between said junctions, an inductance connected in parallel with said junctions, means for supplying current to said junctions, said first and second junctions being of different sizes such tHat when said current is supplied, the maximum Josephson current of said first junction is surpassed and current flowing in said control line equals the minimum Josephson current of said second junction.
Claim 11
Dependent Claim
52 words
A Josephson junction device according to claim 1 wherein said means for reading includes at least a single control element disposed in overlying relationship with said device and means coupled to said device and said control element for applying coincident gate and control currents, respectively, to said device and said control element.
Claim 12
Dependent Claim
73 words
A Josephson junction device according to claim 10 wherein said means connected to said device and said control element include sources connected to said device and said control element, the current magnitudes and polarities of which, to read one binary condition, are insufficient to change the condition of said device, and, the current magnitudes and polarities to which, to read another binary condition, are sufficient to switch said device between said vortex modes.
Claim 13
Dependent Claim
26 words
A Josephson junction device according to claim 11 further including means connected to said device for sensing the switching of said device between said vortex modes.
Claim 14
Dependent Claim
133 words
A Josephson junction device according to claim 12 wherein said sensing means includes a first inductance disposed in series with said device, a first Josephson junction, means for applying a current through said first junction, a resistance disposed between said first Josephson junction and said first inductance, a second inductance connected in parallel with said first Josephson junction via a control conductor, said first junction being biased to be normally in the superconducting state and switchable to the voltage state in response to the appearance of a sense signal when said device switches between said vortex modes, and, a second Josephson junction adapted to provide an output signal in response to the diversion of current from said first junction into second inductance of said control conductor when said first Josephson junction is switched.
Claim 15
Dependent Claim
126 words
A Josephson junction device according to claim 12 wherein said sensing means includes an inductance disposed in series with said device, a first Josephson junction, a resistance disposed between said first junction and said first inductance and connected to said first junction via a control conductor, means connected to said first junction for biasing said first junction to an operating point close to spontaneous resetting such that in response to the appearance of a sense signal when said device switches between said vortex modes said first junction switches from the voltage state to the superconducting state increasing the flow of current in said control line, and, a second Josephson junction adapted to provide an output signal in response to the increased current in said control line.
Claim 16
Dependent Claim
47 words
A Josephson junction device according to claim 1 wherein said means for reading includes means connected to said device and said control element for switching between vortex modes for one stored binary condition and for maintaining said device in an unchanged state for another stored binary condition.
Claim 17
Dependent Claim
73 words
A Josephson junction device according to claim 15 wherein said means connected to said device and said control element includes sources connected to said device and said control element, the current magnitudes and polarities of which, to read one binary condition, are insufficient to change the condition of said device, and, the current magnitudes and polarities of which, to read another binary condition, are sufficient to switch said device between said vortex modes.
Claim 18
Dependent Claim
26 words
A Josephson junction device according to claim 16 further including means connected to said device for sensing the switching of said device between said vortex modes.
Claim 19
Dependent Claim
133 words
A Josephson junction device according to claim 17 wherein said sensing means includes a first inductance disposed in series with said device, a first Josephson junctiOn, means for applying a current through said first junction, a resistance disposed between said first Josephson junction and said first inductance, a second inductance connected in parallel with said first Josephson junction via a control conductor, said first junction being biased to be normally in the superconductive state and switchable to the voltage state in response to the appearance of a sense signal when said device switches between said vortex modes, and, a second Josephson junction adapted to provide an output signal in response to the diversion of current from said first junction into second inductance and said control conductor when said first Josephson junction is switched.
Claim 20
Dependent Claim
125 words
A Josephson device according to claim 17 wherein said sensing means includes an inductance disposed in series with said device, a first Josephson junction, a resistance disposed between said first junction and said first inductance and connected to said first junction via a control conductor, means connected to said first junction for biasing said first junction to an operating point close to spontaneous resetting such that in response to the appearance of a sense signal when said device switches between said vortex modes said first junction switches from the voltage state to the superconducting state increasing the flow of current in said control line, and, a second Josephson junction adapted to provide an output signal in response to the increased current in said control line.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |