This talk will cover practical challenges for cryogenic CMOS designs for next-generation quantum computing. Starting from the system level, it will detail the design considerations for a non-multiplexed, semi-autonomous, transmon qubit state controller (QSC) implemented in 14nm CMOS FinFET technology. The QSC includes an augmented general-purpose digital processor that supports waveform generation and phase rotation operations combined with a low-power current-mode single sideband upconversion I/Q mixer-based RF arbitrary waveform generator (AWG).
Implemented in 14nm CMOS FinFET technology, the QSC generates control signals in its target 4.5GHz to 5.5 GHz frequency range, achieving an SFDR > 50dB for a signal bandwidth of 500MHz. With the controller operating in the 4K stage of a cryostat and connected to a transmon qubit in the cryostat’s millikelvin stage, measured transmon T1 and T2 coherence times were 75.5μS and 73 μS, respectively, in each case comparable to results achieved using conventional room temperature controls.
In further tests with transmons, a qubit-limited error rate of 7.76×10-4 per Clifford gate is achieved, again comparable to results achieved using room temperature controls. The QSC’s maximum RF output power is -18 dBm and power dissipation per qubit under active control is 23mW.
Sudipto Chakraborty received his Bachelor of Technology from the Indian Institute of Technology, Kharagpur in 1998 and his Ph.D. in electrical engineering from Georgia Institute of Technology in 2002. He worked as a researcher at Georgia Electronic Design Center (GEDC) till 2004. From 2004 to 2016, he was a senior member of the technical staff at Texas Instruments where he contributed to low-power integrated circuit design in more than 10 product families in the areas of automotive, wireless, medical, and microcontrollers.
Since 2017, he has been working at the IBM T. J. Watson Research Center where he leads the low-power circuit design for next-generation quantum computing applications using nano CMOS technology nodes. He has authored or co-authored more than 80 papers, and two books, and holds 89 US patents. He has served in the technical program committees of various conferences including CICC, RFIC, and IMS, and has been elected as an IBM master inventor in 2022 for his contributions. He serves as an associate editor of the transactions of circuits and systems – I (TCAS – I) and as a distinguished lecturer in the IEEE CASS and SSCS societies.