Researchers achieve quantum control of an oscillator using a Josephson circuit

erek

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Quantum control of an oscillator using a stimulated Josephson nonlinearity

"Superconducting circuits extensively rely on the Josephson junction as a nonlinear electronic element for manipulating quantum information and mediating photon interactions. Despite continuing efforts in pushing the coherence of Josephson circuits, the best photon lifetimes have been demonstrated in microwave cavities. Nevertheless, architectures based on quantum memories require a qubit element for logical operations at the cost of introducing additional loss channels and limiting process fidelities. Here, we directly operate the oscillator as an isolated two-level system by tailoring its Hilbert space. Implementing a flux-tunable inductive coupling between two resonators, we can selectively Rabi drive the lowest eigenstates by dynamically activating a three-wave interaction through parametric flux modulation. Measuring the Wigner function confirms that we can prepare arbitrary states confined in the single-photon manifold, with measured coherence times limited by the oscillator intrinsic quality factor. This architectural shift in engineering oscillators with stimulated nonlinearity can be exploited for designing long-lived quantum modules and offers flexibility in studying non-equilibrium physics with photons in a field-programmable simulator."


https://phys.org/news/2019-12-quantum-oscillator-josephson-circuit.html
 

tangoseal

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Quantum tech will NEVER be used for the good of mankind. Only nefarious Nazi bullshit. Nothing the elites control is meant for the enhancement of humanity, moving towards the stars, bettering our species. Nope. Just nefarious control grid dystopia.
 

blandead

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One day... How computers work will stop making sense to 99% of people

Quantum tech will NEVER be used for the good of mankind. Only nefarious Nazi bullshit. Nothing the elites control is meant for the enhancement of humanity, moving towards the stars, bettering our species. Nope. Just nefarious control grid dystopia.
Um.. LED lightbulbs are a result of "quantum tech". Also your phone, GPS, Wi-Fi. I'm just gonna stop at those.

Another interesting fact... Einstein was German, and certainly not a Nazi.
 
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Mazzspeed

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I believe White Rose has already overcome this limitation as Elliot Alderson is about to find out...
 

Nenu

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Quantum control of an oscillator using a stimulated Josephson nonlinearity

"Superconducting circuits extensively rely on the Josephson junction as a nonlinear electronic element for manipulating quantum information and mediating photon interactions. Despite continuing efforts in pushing the coherence of Josephson circuits, the best photon lifetimes have been demonstrated in microwave cavities. Nevertheless, architectures based on quantum memories require a qubit element for logical operations at the cost of introducing additional loss channels and limiting process fidelities. Here, we directly operate the oscillator as an isolated two-level system by tailoring its Hilbert space. Implementing a flux-tunable inductive coupling between two resonators, we can selectively Rabi drive the lowest eigenstates by dynamically activating a three-wave interaction through parametric flux modulation. Measuring the Wigner function confirms that we can prepare arbitrary states confined in the single-photon manifold, with measured coherence times limited by the oscillator intrinsic quality factor. This architectural shift in engineering oscillators with stimulated nonlinearity can be exploited for designing long-lived quantum modules and offers flexibility in studying non-equilibrium physics with photons in a field-programmable simulator."


https://phys.org/news/2019-12-quantum-oscillator-josephson-circuit.html
lol, this reads almost like inserted tech words on a Star Trek episode.
I follow parts of it then some bits make me chuckle.

I am really glad you make tech threads like this btw.
 
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Shoganai

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lol, this reads almost like inserted tech words on a Start Trek episode.
I follow parts of it then some bits make me chuckle.

I am really glad you make tech threads like this btw.
Reminds me of this joke terminology video:

 

KD5ZXG

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Still trying to bend my noodle around the decades old Quantum Flux Parametron.
QFP's use Josephson junctions, but don't do quantum logic or interface with light.
So, I know even less what chimeric pigmonkey they gone off about this time...
Why exactly did I want a microwave cavity? Won't any generic resonance do?
Was the cavity so it can interact with light maybe? Totally guessing here...

If "parametric flux modulation" from the article is anything like parametrons of old:
You need pump that injects power at twice the tuned frequency to keep it going.
Maybe pump is light aimed at the cavity? But they said flux modulation, not light.
Are they aiming flux at cavities to pump them? But they said interact with light.
Make up you damn minds...

Also a non-linearity (Josephson junction in this case) to boost the amplitude on
both positive and negative swings, but no pump energy to boost zero crossings.
Keeps zero crossings of multiple devices phase locked to 1/2 the pump freq.
Each parametron is free to lock in 0 or 180 degrees binary phase shift key.
Thus each amplifies weak bits (or vote of inputs) to full scale oscillation, and
stores a 0 or 1 result in the form of phase.

Binary majority vote logic is not "quantum" to extent of leveraging superposition
or entanglements, even when done in quantum ways. A hard choice of phases
that cancel when superposed resolve qubits to normal bits. I suspect whoever
wrote or plagiarized that article had even less clue...

Lets just throw Hilbert Space around to further confuse shit...
 
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TheBuzzer

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I think they are just saying they did something in a better way.
 

KD5ZXG

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So, how can a superconductor have a useful non-linearity?
Useful in this case to pump an oscillation representing data.

Does it work similar to negative resistance: no such thing.
But special diodes can exibit negative dynamic resistance
where the slope of its resistance curve might bend down.

Josephson slope doesn't bend down, it just goes 0 flat.
Always after a tiny voltage drop like a bidirectional diode.
So the actual Volts/Amps is never zero, just the slope.
https://en.wikipedia.org/wiki/Josephson_voltage_standard

But Josephsons and Pi Josephsons are somehow not
the same thing. Flat part of a Pi josephon seems to exist
at true zero. Perhaps can superconduct with zero drop?
https://en.wikipedia.org/wiki/Pi_Josephson_junction

Pi also said to be AC voltage to frequency converters,
but how you apply an AC or DC voltage to something
that begins without a resistance, except to saturate it?
Do I misunderstand correctly that like a capacitor of
oppositeness, flips the phase of AC passing through?

I'm thinking with a DC voltage bias and no DC current,
it becomes a superconductor (and phase flipper) of AC
on the flat part of the slope. This AC (storing the data
as a binary phase shft key) is looped back through an
inductor with another 180degree phase shift and also
where the endless loop of DC current is stored.

Not plain unmodulated DC, wouldn't be interesting...
If you might alter the phase shift of this J junction by
manipulating DC current in the loop, you might pump
parametric oscillation, just as Goto did by saturating
old fashioned inductor capacitor tanks in the 1950's.

So, in actual operation: Maybe the junction does not
operate at point of 180 phase shift, but -90 or +270?
An inductor has maximum 90 degree shift, not 180...
How else could AC circle back to 0 or 360 phase?

Still don't make any sense, since this is at zero volts.
How do you modulate zero? All you gots is current...
 
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KD5ZXG

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If you replace inductor with a delay line, coax or something.
Can you work with multiple bits round robin in one device?

BPSK could be streaming both directions simultaneously.
Don't know if thats an actual mess, or inconsequential.
 
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KD5ZXG

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No clue of what all that OP gibberish gone on about.
Quantum anything doesn't yet make full sense to me.

Tuned circuits don't spontaneously oscillate themselves.
Nor have any reason to stay in phase lock with others.
So, you need a non-linear element energized by clock.

The clock pulses twice as fast as the desired oscillation.
Ocillation peaks of either phase in time with that clock
will be amplified. Any other noise or attempted phase
drift is not repeatedly amplified and decays away.

Somewhere in the machine, an oscillator is dedicated to
maintain reference zero. Else we would not know ones
from zeros. Both look identical except for Binary Phase
Shift Key and that reference zero to compare against.

Hitachi used ferrite shirt buttons as the non-linear element.
http://museum.ipsj.or.jp/en/computer/dawn/0015.html
Until you understand how the old ones worked, ain't much
point complicting things with quantum.

Inputs were mixed like audio, and whichever phase was
in the majority would be the phase amplified to full scale.
An answer would be held untill the clock was turned off
and the tuned circuit allowed to ring down to a state of
undecided, ready to take a new vote.

Each oscillator was a complete ALU and storage bit.
The majority of A,B,1 is the same operation as OR.
The majority of A,B,0 is the same operation as AND.
The majority of A,B,C exactly the same as CARRY.
I/O was usually differential pair. Inversion was free.
NAND and NOR are well known universal logics.
Minority vote of A,B,C is therefore also universal.

The undecided state was more similar to superposition
than today's familiar tri-state. But the noise floor was
always more than any macroscopic ancient qubits held
in undecided superposition. Without inputs, you simply
amplified a random vote from noise.

Now we have ALU, Memory Bit, and RNG. Does it do
anything else? Especially quiet ones, far more quiet
than transistors, have been used to amplify weak radio
(below the noise floor but correlated with the clock)
from distant spacecraft. To resolve qubits from other
quantum logic into normal bits. It also Juliennes fries.

Inputs were rarely mixed strong enough to overwhelm
any stored full scale oscillation. Once vote was decided,
later input changes were typically ignored. Asynchronus
gatelike logic flow is not the usual way for Parametrons
to pass data.

When an undecided Parametron is woken by clock, it
listens for votes from both inputs and outputs. Those
annoying output votes need to be put to sleep first.

Syncronus logic flow involves a rolling wave of quiet
forgetfulness as banks ahead of new votes are powered
down. New logic can only appear in the wake. Requires
a minimum of three clock banks (see the back side of
Hitachi's Hipac module from the museum link above).
You can make a shift register rotate in either direction or
logic flow backward just by how you choose to clock it.

Newfangled quantum ones seem to be using four banks.
Not sure, but suspect a mixing manifold stage was added.
Since superconduct obviously won't use resistors to mix.
And here the inputs might be same strength as full scale.
Preventing backwards flow is more complicated.

If anyone this side of a paywall knows better, please clue me.
 
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erek

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No clue of what all that OP gibberish gone on about.
Quantum anything doesn't yet make full sense to me.

Tuned circuits don't spontaneously oscillate themselves.
Nor have any reason to stay in phase lock with others.
So, you need a non-linear element energized by clock.

The clock pulses twice as fast as the tuned oscillation.
Ocillations in phase with 1/2 the clock are amplified.
Any other noise or attempted phase drift decays away.

Somewhere in the machine, an oscillator is dedicated to
maintain reference zero. Else we would not know ones
from zeros. Both look identical except for Binary Phase
Shift Key and that reference zero to compare against.

Hitachi used ferrite shirt buttons as the non-linear element.
http://museum.ipsj.or.jp/en/computer/dawn/0015.html
Until you understand how the old ones worked, ain't much
point complicting things with quantum.

What gibberish? :(
 

KD5ZXG

Limp Gawd
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Messages
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The kind of gibberish below the noise floor that doesn't correlate with any clock.

Maybe these two pages explain it better...
105535_Parametron_Works.png


Only the shirt button magamp (labeled "Excitation" in diagram above) is
replaced by a Josephson Junction. From that point, you are on your own...
 
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erek

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The kind of gibberish below the noise floor that doesn't corrrelate with any clock.

Maybe these two pages explain it better...


Only the excitation magamp (shirt button) is replaced by a Josephson Junction.
From that point, you are on your own...
excited?
 

KD5ZXG

Limp Gawd
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Excited? Yes, mix of correlated clock and data in nonlinearity results in amplification.
Its been done without electricity using only light and non-linear optical crystal.
Versatile way to make logic from whatever without transistors.
 
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erek

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Excited? Yes, mix of correlated clock and data in nonlinearity results in amplification.
Its been done without electricity using only light and non-linear optical crystal.
Versatile way to make logic from whatever without transistors.
To be honest, i've been legitimately working through the notion of virtualizing the hardware clock as in getting rid of a hardware oscillator / quartz crystal. I'd like to have a purely software defined clock reference.

my initial thoughts were to digitally sample / record a hardware clock signal to use as a reference.

the idea is like a /dev/random *nix device


scope this out KD5ZXG https://en.wikipedia.org/wiki/Asynchronous_circuit#Asynchronous_CPU
 

KD5ZXG

Limp Gawd
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Yup, thats async. Gates naturally do that. Parametrons don't...

Then again, if an async circuit needs 20 stages, doesn't get
a free pipeline to work on multiple threads. Parametron does.

Compartmentalized by rolling waves of sleep, could work six
and 2/3 operations in the pipe simultaneously. Always integer
though, like bleen: Sometimes six, sometimes seven. I would
just stretch that pipe with a do-nothing stage so 7 always fit.

No rule forbids using both techniques in the same circuit.
 
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