Quantum Jump is a unicorn stallion who recently moved to Ponyville after leaving Canterlot University.
Quantum is a generally friendly stallion, who is always ready to help somepony in need. However, he can get a bit caught up in his thoughts when he has problems of his own, and can seem distracted at times. This is also the case when he comes up with a new idea (a common occurrence), at which point he often thinks through the possibilities of his idea, often out loud, an completely oblivious to whatever may be going on around him.
Life in Canterlot
Quantum was born into a relatively well off family. They were not Bluebloods by any means, but he definitely didn't want for anything during his foalhood. His father was a successful business coach, and his mother an accountant for an important Canterlot firm. He got along very well with his sister, Rock Steady (or 'Roxie'), and they were inseparable as foals.
QJ got his cutie mark one day when he was playing in the back garden with Roxie. She accidentally broke one of her favourite dolls clean in half, and he manage to use his magic to fuse it back together, good as new. At that point, his cutie mark appeared. Unfortunately, nopony in his family had any idea what the cutie mark actually meant, and this remained a mystery until several years later.
Quantum did very well at school, and was slightly above average when it came to magical ability. This stood him in good stead when his ability attracted the attention of one professor Volatile Solution, from Canterlot University, because he had the knowledge and resources to finally decipher the true meaning of Quantum's cutie mark. It turned out that the mark originated in an ancient, now dead, civilisation, and it was a symbol representing change, fluidity, and the possibility to improve the current state of things. Volatile took the young Quantum under his wing as an apprentice of sorts, and helped to guarantee a place for him in Canterlot University, although he never did tell Quantum what the cutie mark actually meant...
At Canterlot University, Quantum was in his element. He majored in alchemy, due to his already proven ability at transmutation magic, studying under Volatile Solution. However, he felt stifled, because his ability meant he didn't have to use the chemicals and potions the course focussed on. Unfortunately, he couldn't summon up the courage to tell Volatile, for fear of hurting his mentor's feelings.
After leaving university, Quantum helped Volatile with his research for a short time. However, they soon fell out, because Quantum felt that his mentor's methods were too intrusive, often damaging the test subjects. In a short time, the two decided that it would be for the best if they parted ways, but thankfully they did this on friendly terms. Quantum decided to move to Ponyville, to take advantage of the fact that it was the home of Twilight Sparkle, often cited as one of the most knowledgeable ponies in all of Equestria.
Moving to Ponyville
When he moved to Ponyville, Quantum expected to find a quiet, quaint little town where he could carry out research for his old professor Volatile Solution in peace and quiet, away from the other researchers. However, his expectations were soon proven naive. After securing a house for himself, he visited the Treebrary for the first time, to find a book on transmutative magic. Unfortunately, he found Twilight in the midst of mourning for the recently deceased author Ray Bradbury, resulting in a slightly awkward conversation. He returned home and used his magic to fashion a welcome mat out of grass he picked in his front garden.
His welcome to the town was cemented the next day, when, on a trip to the market, he encountered Cotton Cloud and Pinkie Pie in the middle of a publicity stunt. This involved Cotton flying around town with Pinkie on her back, while Pinkie used her party cannon to carry out... precision cotton candy deliveries. After recieving a clump to the face, Quantum accepted the probable insanity of most of the town's inhabitants, and he found that he liked it better that way.
On QJ's first Summer Sun Celebration as an inhabitant of Ponyville, Twilight organised a large party of ponies to go to Tackyland for a holiday. Although he missed almost all the notices about the upcoming trip, he fortunately managed to find out about it from Splashie -- half an hour before the train was due to leave. One very rushed packing spree later, he managed to get to the train on time, and they set off.
Onboard the train, QJ made friends with Dashing, a young colt who was less than happy that he had to come to Tackyland and leave his best friend, Banana Splits, behind. However, Quantum was able to cheer him up by admitting his shared dislike of roller coasters, and they had a great first day at Tackyland together.
During the rest of the trip, Quantum was very active at the various fairground competition stalls, such as coconut shies. He was also very successful, managing to win an extremely large number of very big plushies. His proudest achievement was winning at the coconut shy, where the owner was cheating, and recieving a giant manticore plushy, bigger than himself.
The Right Path?
A short time after returning to Ponyville from Tackyland, Quantum was feeling torn. He wanted to continue research into the same areas as Volatile, albeit with his own methods, but he felt in his gut that it wasn't what he was meant to do. These thoughts gnawed on his mind, until he happened to meet a humongous pegasus named Wind Cheer. Wind seemed very interested in Quantum's cutie mark, which sparked Quantum's interest, as he never had found out what it actually meant. After a talk with Wind, it turned out that the cutie mark was in the language of the Ancient Mesoponytamians, an extremely magical, and now extinct, culture.
The cutie mark itself was a symbol known as the Quicksilver Rune, and it represented the practice of Mesoponytamian Alchemy, the use of magic circles to channel large amounts of unicorn magic, along with some other reagents, into changing one thing into another thing completely.
This piqued Quantum's interest, and he decided to pay his old mentor Volatile a visit at Canterlot University. When he got there, he found Volatile to be much more accepting of his lack of motivation than he had expected. Volatile happily agreed to sign a note allowing Quantum access to the Starswirl the Bearded wing of Canterlot Library, in order to carry out more research into the Ancient Mesoponytamians.
Quantum spent the next three days in the STB wing 24/7, his muzzle in dusty old books. Eventually, he found what he was looking for: a treatise on the actual practicalities of Alchemy. He learnt about the principles of creating transmutation circles, how to use them to both transmute and enchant objects, and - most importantly - the creation of Hydrargyrum, the magical substance used to actually create transmutation circles.
He rushed back to the University, and placed a very strange monthly order: 20 lbs cinnabar ore, 5 oz pure silver, one small phial of prometheum, and one bottle of krypton. He also purchased a small magical furnace in Canterlot. The total cost of it all was 1,500 bits.
He then returned home, extremely excited to test out his newest knowledge.