"Hey, Onii-chan, what's the computer quantum?"

--How many big siblings can actually exist in this world who can provide adequate answers smoothly and in place, having asked such questions the first year of high school imouto-san who is not superior in Mathematics or Physics, and in the first place, may have little understanding even about the structure of the Neumann-type computer?

At the very least, I'm not like the super onii-sama, so I floated the fava beans on the table after only having pierced the fork into them, and hummed for a moment.

"Hmmmmmm"

At that moment, my imouto-san gave an expression of apology from the bottom of his heart, and lightly lowered his head.

"Ah, sorry, there are things you do not even know, Onii-chan, right? I do not have to ask you all the time, and I have to try to find it myself once in a while. "

It's a tough creature in the position of a «Onii-chan», because I do not obey back down now can be that he said that. While the fava beans are still suspended, I clear my throat with 'ahem'.

"Nothing, well, that's not it, I'll explain it to you if the explanation is rough enough."

"Yes!"

Nodding eagerly, my sister, Kirigaya Suguha, smiled innocently.

Our mother, who works as a digital news-type magazine editor, will almost certainly not wake up, so, for Saturday and Sunday breakfast, Suguha and I have grown accustomed to preparing enough for three, but eating with just the two of us. Today's menu is easy to make risotto with canned white sauce, a salad of romaine lettuce, cauliflower and fava beans, fresh blueberry yogurt and cafe au lait with lots of milk.

After sending fava beans into my mouth with my right hand, I first started talking to clear the way.

"Well, first of all, what quantum is ......"

"I know a lot. This is a basic particle! Like atoms, or electrons. "

Without a moment's delay, I find fault with what Suguha said in a moment.

"Vuvu (1) -. It's a double fault. "

'Wha, where?'

"First of all, an atom is not a fundamental particle. Because the atoms are made of protons, neutrons and electrons. "

'Then, three are elementary particles?'

"Old Vuvuvu textbooks might describe it as such, but now, out of three, only electrons remain as elementary particles. This is because protons and neutrons are found to be formed from even smaller grains called «quark». In other words, quarks are elementary particles. "

After adding 'at least, for now' in my mind, I point out a second error.

"Also, quanta is not the same as elementary particles."

"Wha ......?"

"'The basis of particles' is an expression that denotes« existence », but 'quantum' is a word that must indicate« state »......"

"Whaa ......?"

at this point, a small question mark size was already hanging over Suguha's head, so I quickly commented on that.

"I-in other words, elementary particles are the smallest unit of« material », and quanta is the smallest unit of quantity» «physical ......"

Suguha question mark grows medium size. If he stumbles at this point, then there is no way we will get to the quantum computer.

"A-well, I'll explain by analogy. This risotto is about two hundred ...... there are three hundred kilocalories, right? "

After I said that, Suguha nodded, though it made the expression a bit fun.

"Then this risotto grain is a basic particle that can not be decomposed further and should only produce 0.001 kilocalories ...... in other words, one calorie, right?"

"Well, that's not possible. If I am not mistaken, we have learned that full rice has about three thousand grains, so if we consider that there are many grains, a grain has three hundred divided by three thousand, 0.1 kilocalories ...... A hundred calories, right? ? To get one calorie, you have to divide the grain of rice into a hundred pieces. "

"But, since this is a basic particle, you can not do that. In other words, calories, nothing, this risotto energy can only be represented as a grain of rice ...... has a value of a hundred calories each scattered here and there. Consider the concept that the smallest amount of this energy is quantum. "

'Hmm ...... it's like I got it, and did not get it ......'

Suguha still makes a vague expression, but I do not know how long it will take if we get stuck here, so I have to force my way through.

"Well, in practice, you can split a grain of rice into the many parts you want, but in the case of, for example, electrical energy, the smallest unit is an electron and completely indivisible, so electrons are in a quantum case. Light energy also has the smallest unit, and that's a photon. It's also quantum. In other words, quantum is a way of referring to elementary particles through a focus on «can not they split each property further» ...... though I wonder if its fine if I say it like that. "

'Uh huh.'

This time having seemed to understand it one way or another, Suguha put a single grain on the tip of his spoon and sucked it with a shrivel-up mouth.

"Then, quantum is not an object, but a unit, is it?"

Although I felt that it was still possible to agree when asked that way, but I decided to say 'yes' despite a minor error, and nodded.

"Yeah, well, it's fine to think that way for now. So, we end up back to the beginning ...... A quantum computer is, just like that! a computer that uses quanta! "

"'Ta-dah', completing my sentence while making as SE striking (2) in my heart, I dampened my throat with cafe au lait, temporarily sighed with relief that this ended without any problems. However.

"Hey - you - know That much, who knows It's like when someone asks 'what kirikaeshi gosuku»! (3)', you will answer 'it's five rules when doing kirikaeshi'!

After he immediately replied like that, I looked closely at the face of my sister who is a member kendo club Indeed, kirigaeshigosoku or something seems terminology kendo ;. I do not understand anything other than that.

"...... I- I'm sorry, then I will continue ..."

'Uh-huh, do not mind.'

'............'

After stuffing my cheek with a spoon of risotto cream with cheese for my energy filling, I considered the way I would handle a more difficult problem. First, I must definitely start with this huh.

"Err, Suguha-san. Regarding the computer we usually use, the so-called Neumann-type ... .. the explanation needed ... right? "

"What is that?"

'This is necessary, yes.'

Preparing for a long explanation, I cleared my throat again.

"Err, well, simply put, Neumann-type is an arithmetic of only 0 and 1 ...... in other words, operated by a binary number. the information represented by a set of 0 and 1 is 1 bit. If it becomes eight sets, then it's 8 bits. the 128-bit spearhead of the CPU can process 128 sets of 0s and 1s at the same time. "

'Hmm ...... and that's amazing?'

"that! there are only two ways you can express 0 and 1 with that 1 b. If it's 2 bits, there are four ways: 00, 01, 10, 11; if we convert to a decimal system, it would be 0, 1, 2 and 3. Then, if we have 4 bits, how many ways can it be expressed in? "

"Eight ...... no waiting! Err ...... If we take 2 bits have four ways, 3 bits have eight ways, then 4 bits have sixteen ways?

"Oh right. In other words, the numbers can be handled with 4 bit CPU 0-15. "

"Hmmm. When the bits rise, something good happens? "

Being asking this question with a serious look, I can not answer directly. There must be a lot of great things about it, but when it comes to giving an example that even Suguha can understand ......

"Well, for example, if we take 32 long bits of OS, then the memory can only use 4 gigabytes at max, but if it is a 64 bit OS, in theory, it could use 16 exabytes, or 17.2 hundred million gigabytes. .... "

"Whaa, old personal computer only has 4 giga worth of memory? Although an AmuSphere has many times more ... "

'S-see, bit boost is a good thing, right?'

One way or another, I seem to have conveyed the idea to him, so, after I drank a sip of cafe au lait, I went back to the stream of conversation.

"...... Then, let's count again, how many ways can a number be handled by with 128 bits expressed in?"

"Hm-err ...... s- because multiplying by two, 5 bits have thirty two ways, 6 bits have sixty four ways, 7 bits have 128 ways, 8 bits have 256 ways ...... I can not do it up to 128 with mental arithmetic at this level! "

"Yes, I can not do it either. In other words, it's 2 power 128, so let's see ... "

As expected, there's no way I can handle those numbers with mental arithmetic, so I tried counting with the portable terminal left on the table.

"Let's see ...... 340282366920938463463374607431768211456 way, it seems. Thirty-nine digits, yes ...... What will be the highest denomination in the number of kanji to reveal this ......? Ten hundred thousand people (4) ....... "

"I do not know anything like that, let's leave it as a super big number! I mean ...... if even when a personal computer is capable of doing such an unthinkable amount of calculation, then there is no need to quantum a computer already! "

I hurriedly stopped my imouto-san who, with just a single stroke, cut out a dreaming machine that scientists from around the world are researching with their maximum efforts.

"W-wait wait. Even as usual 128 bit CPUs are poor in some ways. "

'...... Like what?'

'For example, Prime decomposition factor.'

Hearing that, Suguha made an expression that said 'what is it?' "

"That's what you learned in high school, right? It expresses integers as their composite primes, right? I do not remember it being so troublesome though. "

"Oh, now you've said that. Then, what about trying to decompose 33 to prime numbers? "

"Let's see, it can not be split in two, so if we divide it by 3, we get 11 ...... it is prime number, so it's final. The answer is 3 X 11. "

"Correct. Then ...... "

'How does decaying 7663 become a major factor?'

'UII!?'

Making a weird sound, Suguha furrowed her forehead, and after thinking about it, began to tamper with her own portable terminal.

"With 3 ...... integral, 5 obviously will not do, 7 ...... well will not, 11 well, 13 well, errr, now what is the next prime ......"

"Look, it's not that simple, is it? By the way, the answer to the current problem is 79 X 97. Asking questions is easy, but that can only be divided into two primish primes. "

"Ugh, I guess I get the point ...... Ah, but, if you use a computer, it will take like the moment with the current calculation, right? It can only divide the 7663 by the prime number in turn and give an answer if it goes all the way to 79. "

"Yes, something like that. With this number of numbers, it will not even take a tenth of a second. However, prime numbers go a long way. As the digit numbers become larger, the time required to increase decomposition exponentially. Prime factor decomposition is used for "RSA cryptosystem" which even helps us on the net, but, if you decide to decipher currently used 2048 bits - ...... in other words, a 617 digit - key to prime numbers using a Neumann -type of computers, it is possible that it could even take ten years or more, even with the world's fastest computer class. "

"TEN YEARS !? ...... You mean that even Yui-chan will take that long? "

when I heard Suguha's question, despite this real world, I finally quickly looked around.

Fortunately, my beloved daughter, top down-type AI Yui did not seem to hear it, so I sighed with relief.

"Hey, do not talk about Yui like that! Knowing, he might say something like 「I'll try it!」 And do not come back for ten years. "

'Ahaha, that seems possible.'

Seeing Suguha laugh carefreely, I sighed. I then throw a quantised risotto cream into my mouth and put my mind to it while chewing the food.

"So, well, there are things that even today the computer is bad at. - But, if the quantum computer is used, it can complete the decomposition of prime factors from even big numbers in the blink of an eye ...... maybe. This is the same as that if used all over the world now, the cipher that appears to be completely secure will end up being swiftly conceded. "

'Hmmm ...... Then, how could a quantum of computers break down quickly?'

As I thought, I would have to explain that too yes, and with that I accidentally closed my eyes. To be honest, I do not have the conviction that I myself really understand the 'how' is capable of it.

However, if I end up giving up here, then what will be the goal of all the tough efforts until now, so I give my go on the challenge of being reckless.

"Well, I explained about the quanta at the beginning."

"Yes. They are grains that can not be further divided. "

"...... W-well, that's right. So, because the quanta is very small, a lot of strange things happen. One of them is something called «superposition state» ...... for example, if you try to close an atom in a small box. Atoms that can rotate either in clockwise rotation, or clockwise counterclockwise, but that does not decide until observation. This does not mean that it is unknown, it has not been decided yet. It's a state when both clockwise and counter-clockwise rotate overlap. "

'Whaa?'

Suguha said, while making 'what does this man say' an expression with his eyes.

"Then just decide which one it is! If you open the box, you'll know right away! "

"Funny you should mention that, since the atoms are super small, once you open the box, their oscillations, rotations and the like will change. Frankly putting, as for why the original quantum of computers does not exist in the current reality, I think that most of the reason is because it's hard to measure atoms ...... in other words, their quantum state, accurately. "

"Hmm ......"

Though still finding it difficult to understand, Suguha nodded.

"...... So, if the rotation of atoms overlaps, something good happens?"

"Yes. For example, if we take that exact rotational state is 0, and the state of the left rotation is 1, then one atom can have information of 1 bit but ...... rotating overlap means that good states 0 and 1 can be made. This is called quantum bits or qubits, but what's important is that, in contrast to existing types of computers that can basically only count one number at a time, quantum computers using quantum bits can count many numbers at the same time. Anyway, as you can see, it's because they overlap. "

'Whaaa?'

"I understand the feeling behind you want to say that very well, Sugu. But, now, please swallow it like that! "

Having just filled her cheeks with fava beans, Suguha's expression was hard to read as she stopped her mouth, but, shortly, she swallowed the seed with a gulp while muttering.

"Well, I'll start with the parts that I understand ...... So, that is, we make a quantum computer with a line of 2048 atoms that can rotate clockwise or counter-clockwise. With that, we enter 2048 a little ...... in other words, a 617 digit super big number that I mentioned earlier, and then describe it to be the main factor. And then the quantum computer can do the prime division at the same time using superposition state, completing the calculation in mere moments, even though it will take on the existing computer decades. Well, what do you think, is not that amazing! "

Suguha threw a glance at me, who had tried to overcome the problem somehow with a lot of effort, with eyes turned upside down and said short, merciless comment.

"Onii-chan, sorry. As for the second half, I really do not understand what you're saying. "


SECTION 2


"...... And that's how it goes. Do not you think he means, Higa-san? "

Listening to me being pulled-out and unemployed complaints continuously, for some reason researchers with spiky hairs, roughly round glasses and wearing T shirts with a retro game logo make a bitter expression and answer.

"What do you say-s (5), Kirigaya-kun. Being able to tell you imouto-chan, a first year highschooler, about a quantum computer is a very rare event, it usually does not happen so soon-s! If your imouto-chan has raised the 'beautiful' flag, then he will likely develop a resurrection for quantum mechanics, and will request a job at Rath in the near future. "

'No way, not at all.'

While giving a firm reply, I looked around the spacious room.

For some reason, the inner chamber of the building in central Tokyo's Roppongi, in other words, is not far from Camp Hinokicho belonging to the former Defense Agency of Japan, completely cramped with engines, with countless cooling fan fans.

The object that I sit on a gel bed attached to the machine feels great. The exterior is made of aluminum which gives off the dim light; the name of the machine, which is so great that it can be called the lord of space, is «soul TranslatorSTL». A machine that translates soul; Such excessive naming is by no means luxurious.

That's because this device is the fourth-generation type of FullDive engine that traps with a light quanta consisting of human consciousness, and allows it to communicate with the soul itself.

And, in a sense, it could be called the world's leading quantum of computers.

While preparing for the dive, the idea struck my mind, and I asked pointy-haired researcher, Higa Takeru, the question.

"Come to think of it, Higa-san, can this STL do 2048 a bit prime factor decomposition?"

"W-anyone-s with questions out of the blue? This can-s, as a quantum controller register is really not enough-s. "

'Then, is it possible if the register is expanded?'

"W-well that will ...... No no I will not have this conversation-s! Some time ago, I received a severe scolding from Kiku-san after he discovered that I had tried to expand the register to get a prize for RSA interpreting the contest, so it really would not happen-s! "

"...... U-understood."

"More importantly, are you ready? I want to start an immediate-s test. "

'OK s'

Nodding, I eased my body into a gel bed. Overhead, a headgear - the type of interface that is completely covered head slowly down.

The reason why I have not told Suguha about this «quantum computer» is that he will definitely have 「I also want to go!」 Tantrum after I told him. However, I am enough for this suspicious 'test live-person' part-time job that wasted a long-awaited Sunday.

Anyway, the last time I did this part time job, I really experienced something strange.

After diving into the abandoned city who knows where instead of VR space meant for the test, I fought against a silver avatar calling himself «Silver Crow». the result is a draw, or rather a truncated connection before a conclusion can be reached. But, despite thinking thoroughly about it, I still can not come up with an answer to the question of what that experiment is.

however, I have my own guesses about it.

I have not said this to Suguha either, but the reason for the event could be because quantum computers can process multiple calculations at the same time, countless quantum registers that exist in the parallel world can also be used -. There is such discussion that is treated as a joke

at that point, can I end up connecting with the same kind of devi ce that exists in a parallel world, or maybe the future? And then fight against «Silver Crow» who uses that device ......?

As a matter of fact, it all sounds like a dream. No, it might really have been a dream.

At least, I can not verify phenomena anymore. That's because such an event might not happen twice.

"Then I started the s-connection."

Hearing the tensionless voice of Higa, I closed my eyelid under my head teeth.

SECTION 3


"...... 'Such a thing will not happen twice', yes ......"

While muttering in amazement, I tried to pinch my right cheek, but the scene in front of my eyes did not disappear.

The test room that I had arranged to dive into was supposed to be a sunny spring jungle. However, there is no ground beneath my feet, no trees around it and no sky above the blue head.

What exists instead is a completely white space, curved in all directions. The interior of a pure white ball, such an expression would probably be the most adequate.

Based on my impression, it is undoubtedly VR space, but because of this, as far as difficult to understand. However, if I assume that my avatar is the same size as mine in the real world, then the diameter of the ball will probably be three hundred meters at least

...... --My avatar?

Turning my mind a little, I see my own body.

In FullDive using the STL, the avatar is basically automatically generated from «self-image» of the connected person. In my previous dive, I made myself from the Online WordSword ArtOperiod that received the nickname «The Black Swordsman». However, when I feel too embarrassed by it, this time I have been asked to use the test -using avatar prepared by default, but--

"............ This time this one, yes ......"

I groaned weakly.

It was not me from the SAO period. However, no matter how I look at it, I'm wearing a coat from Alfheim online ALO, Which Grealy resembles the black overcoat I use back then. Even my favorite one-handed sword is equipped on my back. I do not have a mirror, so I do not know if it even goes as far as reproducing my face, but my hairdo feeling is undoubtedly the same as that for which I used to my avatar in ALO.

Arriving at this point, I had no choice but to accept it. «Same quantum device interference space» week as last has happened.

Assuming that, will that silver fighter, Silver Crow, show up again? However, the feeling of this world is too different. The scope with a diameter of three hundred meters has a pure white outer wall, which, for some reason, only has a curious luminescent pattern, but if not completely clean. In addition, the only existing object is a small disk that I stood on.

"Why is this happening again ......", I murmured with deep breath mixed, but at that moment.

"That's what I want to ask", voice, calm but deep and full of strength, sounding behind me.

Without a moment's delay, I tried to draw a sword on my back reflex as I turned, but stopped my right hand motion during this dangerous moment. It's because I recognize the guy standing on the side of the disk.

Under long dark hair, smart eyes stared intently at me. Her body, which is a few centimeters taller than me, wears a white jacket with emerald green highlights that look like a school uniform. He does not have anything like a school badge on his chest, but can the school badge be an octagonal symbol on both shoulders?

Although I have no uniform memories, the sense of deja vu that I harbor for human essence is not my imagination.

That is indeed «him». Mysterious NPC ...... or maybe a player who appeared a few days ago in a campaign search in ALO in the show boss role, which is «Giant Buy». He did not tell me his name, so I called him so.

"...... We meet again,« No-nama-san »"

Even though I called him like that, his expression did not move. Apparently the other side recognized me too.

"So you ...... Kirito-kun."

Even as he called my name, the sharpness in his eyes did not disappear. The reason for that becomes clear with the following words.

"Does this mean that you got intertwined with my" reality "this time?"

"...... With reality ...... do you mean that this is the world you live in, No-nama-san? This is not a virtual world? "

I hastily asked back, thinking that STL could not end up connecting with the real world. However, the person lightly shook his head.

"No, that's not what I mean. This space is a «Five Sense of Reproduction-type Virtual Simulator» that I've been experimenting with. But, of course, devices that operate are already installed in the real world. And ...... because no more worries that I will interrupt your quest, I will give my name too. I am «Shiba

Tatsuya »." 'Shiba ...... Tatsuya.'

I really do not remember hearing that name I just repeated. And so, maybe judging this from my reaction, the man's eye named Tatsuya shows the impression of seriousness for a moment.

"...... I see, it does seem to be an accident like last time. In this case, should I take the same steps to undo this country, like last time ...... I wonder ... "

'...... Like last time ......?'

After once again mimicking his words in muttering, I finally remembered. Last time, in other words, when I met him at ALO, at the critical time our swords and spears battle when we simultaneously hit each other, the connection is cut off. And, this is the same as when I have fought against the Silver Crow.

"No, wait. No connections are truncated because the circuits connecting the two worlds are not able to bear the burden of our battle at max speed? ...... In other words, it's possible that other methods will also cause the same phenomenon. "

"Hmm ...... like?"

Being calmly urged by Tatsuya to continue, I eagerly thought about it. The point is that we have to cause a giant load to the world, so ...... just as I discussed up to this point, I am reminded of my conversation with Suguha this morning.

"............!"

I realized realized in wings »« fairy on my back and take off from the disk. I did it because I wanted to get some distance, but, with a twitch of an eyebrow, Tatsuya narrowed his eyes and mumbled 「...... the flight magic, huh」.

The next moment, Tatsuya also climbed from the disc and floated at the same height as me. After signaling him to get some distance, using my imagination, I registered a large number. It's a creation borrowed from a series of STL operations - 2048 bits, key 617 digit cipher.

"Shiba-san. This number is the product of two prime numbers. Try decomposing into primes with devices that operate the simulator. "

In this case, a gigantic load will be placed on the device ...... and consequently, on the circuit linking the world, and must cancel the interference state. That's what I thought, but ...

Shiba Tatsuya's eyes, which float in the air without using wings, are colored with bright blue curious.

The number of 617 digits that I generated also started to glow white. Little by little, all the numbers vibrate, and high tones and frequencies make the world tremble.

---- This guy ... can not be serious.

---- He decomposed 2048 bits to the prime number with mental arithmetic!

Leaving me back shocked, the amplitude of the numbers is steadily increasing to the max. White light finished dying round walls, and scorched my vision.

Before long, the line of numbers began to divide right and left bit by bit .--

As the roar of the world rumbles, it decomposes into two gigantic primes.

The number Shiba Tatsuya began to disappear into the white light. As the infinite space comes falling down, I shout,

"Th-THAT'S IMPOSIBLEEEEE !? IT MUST TAKE TENS YEAR EVEN FOR SUPERCOMPUTEEEEEEER ------ !!

On the verge of a broken world connection, I felt that I could hear Tatsuya's voice responding in surprise.

"......« Decomposition »is my specialty. Let's meet again in a few days, Kirito-shounen. "

(End)


NOTE
1. ^ Bel The sound effects are often done during the quiz show when someone correctly answers the question.
2. ^ Abbreviation for "sound effects".
3. ^ Kirikaeshi (切 り 返 え し, lit "cut repeatedly") is the name of the kendo exercise that involves a succession of strikes. Gosoku (五 則) literally means "five rules".
4. ^ A man (万) is a Japanese number for 10,000. Since Kazuto talks about how to express the number in kanji and there are already a thousand before that person, I decided to leave it untranslated.
5. ^ Higa Takeru has the habit of shortening the verb で す (desu) to ッ ス (SSU).