spin qubit system integration with advanced semiconductor … · 2021. 3. 24. · the ‘fab ’...

Intel ConfidentialDepartment or Event Name 1

Spin Qubit System Integration with Advanced Semiconductor Manufacturing

IEEE Quantum Workforce Development

Lester Lampert, Ph.D.

Quantum Computing Lab

IEEE Quantum Workforce Development 2

Outline

• What is advanced semiconductor manufacturing?

• Why semiconductor spin qubits?

• Spin qubit tutorial

• Porting the traditional FAB flow to spin qubits

• Scaling of semiconductor spin qubit systems

• Summary


What is advanced semiconductor manufacturing?

• The ‘FAB’ is a vast collection of wafer scale tools

• Electronic measurement represents any electrical signal used to develop metrics

• Seeing is believing: correlate electronic measurement with manufacturing targets

The ‘FAB’

Electronic measurement

Seeing is believing


Semiconductor processing steps

Lithography

Chemical Mechanical Polish

(CMP)

Etch

See Y Nishi and R Doering, Handbook of semiconductor manufacturing technology (2000); H Geng, Semiconductor manufacturing handbook (2018)


Transistors are the most ubiquitous man-made objects on earth

Intel 14nm FinFet

Fin Cut

Intel ships ~800 Quadrillion transistors every year (800,000,000,000,000,000)

By 2025 expect more transistors on Earth than human cells! Forbes.com

Gate Cut

https://www.forbes.com/sites/jimhandy/2014/05/26/how-many-transistors-have-ever-shipped/#45d9fd3e4425


ENIAC (ca. 1947-1955) ENIAC (1995)

In ~50 years, ENIAC went from occupying an entire room to an area smaller than a US dime using Advanced Semiconductor Manufacturing

Images from Wikipedia


Quantum Supremacy (2019)

Advanced Semiconductor Manufacturing can transform quantum computers…

Intel Horse Ridge 2 (2021)

All* rack electronics moved onto an SoC inside fridge


Why semiconductor spin qubits?

22

mm

Intel Transmon Test Chip 49 qubits

SameScale3

6 m

m

Intel Tukwila CPU 20082 billion+ transistors


Spin qubits are highly coherent

https://blog.qutech.nl/index.php/2018/04/20/making-quantum-computers-with-spin-qubits/

Metric Best reported value

T1 >1s

T2* 100us

T2Hahn 1ms

T2mem 30ms

F1Q 99.96%

F2Q 98%

Fmeas 98% at 1us

6Q device

Stephan Philips et al. APS March Meeting 2021

Takeda et al. Arxiv 2010.10316 2020

3Q GHZ state


What is a spin qubit?

A qubit is a two-level system, so we need to generate these

two levels

B0

Apply an external magnetic field

𝐸 = 𝑔𝜇𝐵𝐵0

We now have well defined levels to utilize as a qubit!


At low temperature, we can accumulate a 2DEG (two-dimensional electron gas) at a Si/SiOx interface

Silicon

Oxide

++ + ++ + +


Silicon

Oxide

++ + + -- -

Dot 1 Dot 2

Using voltages to push electrons away, we can isolate electrons by forming quantum dots

Gate 1 Gate 2

2DEG reservoir2DEG reservoir


Silicon

Oxide

++ + + -- -

Dot 1 Dot 2

We then apply the external magnetic field we introduced so we can have addressable two-level systems

Gate 1 Gate 2

B0

𝐸 = 𝑔𝜇𝐵𝐵0


Silicon

Oxide

++ + + -- -

Dot 1

Gate 1 Gate 2

Adding or subtracting a single electron from the quantum dot costs a specific energy, the charging energy > kBT

Clean single quantum dot in charge sensing (Intel Si/SiGe device)


Increase barrier gate voltage


Vreservoir

VGate1 VGate1

Spin down Spin up

Vreservoir

EF EF

We have a mechanism for both initialization, and measurement,

ȁ ۧ0

TimeCh

arge

sen

sor

curr

ent

TimeCh

arge

sen

sor

curr

ent


Spin up

Spin down

By applying a threshold to our ‘blip’ data, we can detect a spin up event

threshold

Before

After


Phase = 0 Phase = 0 Phase = 90 Phase = 90

X90 Y90

Single qubit operations/gates are rotations around the Bloch sphere

X Y

Changing the phase by 90° we can rotate around the y-axis

Bit flip (x) Bit flip (y)

Z

Rotation about the z-axis is done in

software by applying a global phase to all

X and Y gates


𝐸 = 𝑔𝜇𝐵𝐵0 = ℎ𝑓𝐿

First, we need to find the qubit by sweeping the frequency of a magnetic field applied perpendicular to the external magnetic field, B0

VreservoirVdot

EF

microwaves


Each point corresponds to 2000 ‘blip’ measurementsInit Measure

Init Measure

fL

fL

Sitting at the Larmor frequency, we can rotate the qubit!

A lot of blips at our spin up state

Very few blips at our spin down state


BAC

BDC

IACIAC

Strip line

CPW

CPW

ESR stripline


28SiMOS electron spin qubit coherence times with ESR at ~100mK

T2*

THahn

TCPMG

Intel ESR stripline device performance (SiMOS)

Coherence times in-line with other academic devices.(T2* = 20us, T2Hahn = 290us, T2CPMG = 4ms)


BDC

Spatial oscillation

MicromagnetMicromagnet

Plunger gate

Electrical control with micromagnets


Intel micromagnet device performance (Si/SiGe)

MM magnet fab

Rabi

CPMG 40: T2 = 1.1ms

Coherence times in 5 different devices

Clifford fidelity of 98.8% - limited by nuclear spins: next steps to improve valley splitting and implement multi-qubit gates


Porting the traditional flow to spin qubits

The ‘FAB’

Seeing is believing

NEW!

To implement the FAB cycle with spin qubits, one must introduce cryogenic

measurements

Electronic measurement


The FAB: Intel spin qubit devices

Full 300mm Wafer Full Reticle

Individually diced 55/23/15/ 7 gate arrays


Seeing is believing: process control can eliminate qubit personality

Academic Device Intel Fabrication

TU Delft


Electrical measurements

Room T2 hours / wafer

1000s of devices

1.7 K 12 hours / device

T = 10 mK Weeks / device

Increasing measurement time

Cryogenic measurement represents a major bottleneck and impedes the FAB flow!


Electrical measurements: divide and conquer

300 mm FAB

300mm wafer probing at room temperature

Measurements at <2 Kelvin

Dilution Fridge

1L. Petit et al., PRL 121, 076801 (2018)2L. Petit et al., Nature 580, 355-359 (2020)


Introducing the cryoprober (T<2K)

• Combination of expertise in wafer scale probing and cryogenics

• Full 300mm wafer comes out of the FAB and into the prober

• Able to recover wafer for further processing or move to packaging

• No handling and wire bonding


Exponentially speed up characterization <2KCross-Wafer Device CharacterizationCross-channel capacitance measurements

V1

V2

Gate V1 (mV)

Gate

V2 (

mV

)

Ch 1

Ch 2

Ch 1

Ch 2

From several weeks to 24 hours!


The ‘FAB’

Seeing is believing

RT etest

LT etest

ULT etest

The spin qubit flow


The ‘FAB’

Seeing is believing

RT etest

LT etest

ULT etest

Packaged computing unit


Interconnects and packaging

Processor• 109 transistors• 103 pins

3D NAND Memory• 1012 bytes• 102 pins

55 Gate Linear Dot Array• 26 Qubits• 122 pins

Qubit chips currently have more connections than qubits


Enabling quantum computing with advanced manufacturing

Intel 14nm Interconnect Stack• Fully integrated and

packaged processors utilize many metal layers

• Interconnects, process uniformity, and performance enables scaling

Spin qubits are made on the same processing line that produces these interconnect layers


Scaling qubit control systems


Horse Ridge 1


Horse Ridge 1: microwave drive

• Controller capability• Drive

• Main features• 128 qubits control with frequency

multiplexing(4 channel, each with 32 qubits)

• Arbitrary pulse envelope(SRAM based)

• Wideband frequency output(2-20GHz)

[J. P. G. Van Dijk et al., IEEE JSSC, Nov. 2020]


Horse Ridge 1: microwave drive

Randomized benchmarking

Two qubit gates and the Deutsch-Jozsa Algorithm

Fidelity = 99.71±0.03%

Fidelity = 99.69±0.02%


Horse Ridge 2

• Controller capability• Drive

• Readout

• Gate pulsing

• Additional features• Programmable digital filter for drive

• Integrated micro-controller

• 22 DACs for flexible gate control

• SoC integration: >100M transistorsTechnical details were presented at 2021 IEEE

International Solid-State Circuit Conference (ISSCC)

4mm

Readout

RX

Re

ad

ou

t

RX

Dig

ita

l

Gate Pulsing

Readout

TX

Dri

ve

Dig

ita

l

Readout TX

Digital

Gate Pulsing Digital

Memory

µ-controller

Dig

ita

l I/O

s

Drive

4mm

4mm

Tested and verified at ~4K and currently integrating with spin qubit hardware


Quantum @ Intel


Summary

• The path towards useful quantum computers involves myriad skillsets

• Full breadth of advanced semiconductor manufacturing + quantum computing skills (both experimental and theoretical)

• Getting involved in quantum computing with spin qubits can come from any level in the development flow

• Learning quantum and qubit specialist information is possible on-the-job

spin qubit system integration with advanced semiconductor … · 2021. 3. 24. · the ‘fab ’...

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