Superconducting integrated circuits with clock signals distributed via inductive coupling
Superconducting integrated circuits with clock signals distributed via an inductive coupling and related methods are provided. A method includes providing a D flip-flop having a clock terminal coupled to receive clock pulses from a clock line, a data input terminal, and a data output terminal. The D flip-flop may further include a first Josephson junction (JJ) coupled between a first terminal and a second terminal. The D flip-flop may further include a superconducting quantum interference device (SQUID) coupled between a third terminal and a fourth terminal, where an inductive loop, formed between the first JJ and the SQUID, is configured to in response to receiving a first clock pulse, store a fluxon when a state of the input data signal is high, and is configured to in response to receiving a second clock pulse to annihilate the stored fluxon when a state of the input data signal is low.
1. An integrated circuit comprising:
at least one D flip-flop configured to receive a clock signal, receive an input data signal, and provide an output data signal;
a clock line coupled to provide the clock signal to the at least one D flip-flop; and
a return clock line, wherein the clock line and the return clock line are connected across a stacked driver to provide current for driving the clock signal, and wherein the at least one D flip-flop further comprises:
a clock terminal coupled for receiving the clock signal via the clock line,
a data input terminal coupled for receiving the input data signal,
a data output terminal coupled to provide the output data signal,
a first inductor coupled between the data input terminal and a first terminal, a first Josephson junction (JJ) coupled between the first terminal and a second terminal, and
a second inductor coupled between the first terminal and a third terminal and a superconducting quantum interference device (SQUID) coupled between the third terminal and a fourth terminal, wherein an inductive loop, formed between the first JJ and the SQUID, is configured to in response to receiving a first clock pulse via the clock line, store a fluxon when a state of the input data signal is high, and wherein the inductive loop is configured to in response to receiving a second clock pulse via the clock line to annihilate the stored fluxon when a state of the input data signal is low.
2. The integrated circuit of claim 1 , wherein the clock line is coupled to receive the clock signal from at least one of an off-chip clock driver or a Wilkinson splitter driven by an off-chip driver.
3. The integrated circuit of claim 1 , wherein the SQUID comprises a second Josephson junction (JJ) coupled between the third terminal and the fourth terminal and a third Josephson junction (JJ) coupled between the third terminal and the fourth terminal.
4. The integrated circuit of claim 1 , wherein the clock line is an inductive line.
5. The integrated circuit of claim 1 further comprising a clock distribution network for distributing the clock signals, and wherein the clock line is one or more of transmission lines that are configured to create the distribution network.
6. The integrated circuit of claim 1 , wherein the clock line does not include any Josephson junction transmission line (JTL) components for driving the clock signal.
7. The integrated circuit of claim 1 , wherein each of stacked drivers is a DC-biased stacked driver.
8. A method comprising:
providing a clock distribution network, including a clock line coupled to provide a clock signal comprising clock pulses; and
providing at least one D flip-flop including:
a clock terminal coupled for receiving the clock signal via the clock line,
a data input terminal coupled for receiving an input data signal,
a data output terminal coupled to provide an output data signal,
a first inductor coupled between the data input terminal and a first terminal, a first Josephson junction (JJ) coupled between the first terminal and a second terminal, and
a second inductor coupled between the first terminal and a third terminal and a superconducting quantum interference device (SQUID) coupled between the third terminal and a fourth terminal, wherein an inductive loop, formed between the first JJ and the SQUID, is configured to in response to receiving a first clock pulse via the clock line, store a fluxon when a state of the input data signal is high, and wherein the inductive loop is configured to in response to receiving a second clock pulse via the clock line to annihilate the stored fluxon when a state of the input data signal is low.
9. The method of claim 8 , wherein the clock line is coupled to receive the clock signal from at least one of an off-chip clock driver or a Wilkinson splitter driven by an off-chip clock driver.
10. The method of claim 9 , wherein the clock line does not include any Josephson junction transmission line (JTL) components for driving the clock signal.
11. The method of claim 8 , wherein the clock line is coupled to receive the clock signal from a direct current (DC) biased stacked driver.
12. The method of claim 8 , wherein the clock line is coupled to receive the clock signal from a logical clock resonator.
13. The method of claim 8 , wherein the clock line is coupled to receive the clock signal via an alternating current (AC) biased driver.
14. The method of claim 8 , wherein the clock line is an inductive line.
15. An integrated circuit comprising:
a plurality of data lines for carrying data signals;
a plurality of clock lines for carrying clock signals, wherein each of the plurality of clock lines is configured as an inductive line such that each of the plurality of clock lines does not include any Josephson transmission line (JTL) components for driving any of the clock signals; and
at least one D flip-flop comprising:
a clock input terminal coupled to receive a clock signal from one of the plurality of clock lines,
a data input terminal coupled to receive an input data signal from one of the plurality of data lines, and
a data output terminal coupled to provide an output data signal,
a first inductor coupled between the data input terminal and a first terminal, a first Josephson junction (JJ) coupled between the first terminal and a second terminal,
a second inductor coupled between the first terminal and a third terminal and a superconducting quantum interference device (SQUID) coupled between the third terminal and a fourth terminal, wherein an inductive loop, formed between the first JJ and the SQUID, is configured to in response to receiving a first clock pulse via the clock line, store a fluxon when a state of the input data signal is high, and wherein the inductive loop is configured to in response to receiving a second clock pulse via the clock line to annihilate the stored fluxon when a state of the input data signal is low.
16. The integrated circuit of claim 15 , wherein the one of the plurality of clock lines is coupled to receive the clock signal from at least one of an off-chip clock driver or a Wilkinson splitter driven by an off-chip clock driver.
17. The integrated circuit of claim 15 , wherein the one of the plurality of clock lines is coupled to receive the clock signal from a direct current (DC) biased stacked driver.
18. The integrated circuit of claim 17 , wherein the one of the plurality of clock lines is coupled to receive the clock signal from a logical clock resonator.
19. The integrated circuit of claim 15 , wherein the one of the plurality of clock lines is coupled to receive the clock signal from an alternating current (AC) biased driver.
20. The integrated circuit of claim 15 further comprising a clock distribution network for distributing the clock signals, and wherein the one of the plurality of clock lines is a transmission line that is configured to create the distribution network.